diff --git a/lib/runtime.dart b/lib/runtime.dart
index 5035666..b407c10 100644
--- a/lib/runtime.dart
+++ b/lib/runtime.dart
@@ -2,7 +2,7 @@ library runtime;
 
 import 'dart:io';
 
-import 'package:runtime/src/compiler.dart';
+import 'src/compiler.dart';
 import 'package:runtime/src/mirror_context.dart';
 
 export 'src/analyzer.dart';
@@ -29,8 +29,8 @@ class RuntimePackageCompiler extends Compiler {
   void deflectPackage(Directory destinationDirectory) {
     final libraryFile = File.fromUri(
         destinationDirectory.uri.resolve("lib/").resolve("runtime.dart"));
-    libraryFile
-        .writeAsStringSync("library runtime;\nexport 'src/context.dart';\nexport 'src/exceptions.dart';");
+    libraryFile.writeAsStringSync(
+        "library runtime;\nexport 'src/context.dart';\nexport 'src/exceptions.dart';");
 
     final contextFile = File.fromUri(destinationDirectory.uri
         .resolve("lib/")
@@ -41,9 +41,11 @@ class RuntimePackageCompiler extends Compiler {
         "import 'package:generated_runtime/generated_runtime.dart' as context;");
     contextFile.writeAsStringSync(contextFileContents);
 
-    final pubspecFile = File.fromUri(destinationDirectory.uri.resolve("pubspec.yaml"));
-    final pubspecContents = pubspecFile.readAsStringSync().replaceFirst("\ndependencies:",
-      "\ndependencies:\n  generated_runtime:\n    path: ../../generated_runtime/");
+    final pubspecFile =
+        File.fromUri(destinationDirectory.uri.resolve("pubspec.yaml"));
+    final pubspecContents = pubspecFile.readAsStringSync().replaceFirst(
+        "\ndependencies:",
+        "\ndependencies:\n  generated_runtime:\n    path: ../../generated_runtime/");
     pubspecFile.writeAsStringSync(pubspecContents);
   }
 }
diff --git a/lib/slow_coerce.dart b/lib/slow_coerce.dart
index e7ce986..797e0de 100644
--- a/lib/slow_coerce.dart
+++ b/lib/slow_coerce.dart
@@ -4,38 +4,50 @@ const String _listPrefix = "List<";
 const String _mapPrefix = "Map<String,";
 
 T cast<T>(dynamic input) {
-  if (input == null) {
-    return null;
-  }
-
   try {
-    final typeString = T.toString();
+    var typeString = T.toString();
+    if (typeString.endsWith('?')) {
+      if (input == null) {
+        return null as T;
+      } else {
+        typeString = typeString.substring(0, typeString.length - 1);
+      }
+    }
     if (typeString.startsWith(_listPrefix)) {
       if (input is! List) {
         throw TypeError();
       }
 
-      if (typeString == "List<int>") {
+      if (typeString.startsWith("List<int>")) {
         return List<int>.from(input) as T;
-      } else if (typeString == "List<num>") {
+      } else if (typeString.startsWith("List<num>")) {
         return List<num>.from(input) as T;
-      } else if (typeString == "List<double>") {
+      } else if (typeString.startsWith("List<double>")) {
         return List<double>.from(input) as T;
-      } else if (typeString == "List<String>") {
+      } else if (typeString.startsWith("List<String>")) {
         return List<String>.from(input) as T;
-      } else if (typeString == "List<bool>") {
+      } else if (typeString.startsWith("List<bool>")) {
         return List<bool>.from(input) as T;
-      } else if (typeString == "List<Map<String, dynamic>>") {
+      } else if (typeString.startsWith("List<int?>")) {
+        return List<int?>.from(input) as T;
+      } else if (typeString.startsWith("List<num?>")) {
+        return List<num?>.from(input) as T;
+      } else if (typeString.startsWith("List<double?>")) {
+        return List<double?>.from(input) as T;
+      } else if (typeString.startsWith("List<String?>")) {
+        return List<String?>.from(input) as T;
+      } else if (typeString.startsWith("List<bool?>")) {
+        return List<bool?>.from(input) as T;
+      } else if (typeString.startsWith("List<Map<String, dynamic>>")) {
         final objects = <Map<String, dynamic>>[];
-        (input as List).forEach((o) {
-          if (o == null) {
-            objects.add(null);
-          } else {
-            if (o is! Map<String, dynamic>) {
-              throw TypeError();
-            }
-            objects.add(o);
-          }
+        input.forEach((o) {
+          objects.add(o);
+        });
+        return objects as T;
+      } else if (typeString.startsWith("List<Map<String, dynamic>?>")) {
+        final objects = <Map<String, dynamic>?>[];
+        input.forEach((o) {
+          objects.add(o);
         });
         return objects as T;
       }
@@ -45,23 +57,31 @@ T cast<T>(dynamic input) {
       }
 
       final inputMap = input as Map<String, dynamic>;
-      if (typeString == "Map<String, int>") {
+      if (typeString.startsWith("Map<String, int>")) {
         return Map<String, int>.from(inputMap) as T;
-      } else if (typeString == "Map<String, num>") {
+      } else if (typeString.startsWith("Map<String, num>")) {
         return Map<String, num>.from(inputMap) as T;
-      } else if (typeString == "Map<String, double>") {
+      } else if (typeString.startsWith("Map<String, double>")) {
         return Map<String, double>.from(inputMap) as T;
-      } else if (typeString == "Map<String, String>") {
+      } else if (typeString.startsWith("Map<String, String>")) {
         return Map<String, String>.from(inputMap) as T;
-      } else if (typeString == "Map<String, bool>") {
+      } else if (typeString.startsWith("Map<String, bool>")) {
         return Map<String, bool>.from(inputMap) as T;
+      } else if (typeString.startsWith("Map<String, int?>")) {
+        return Map<String, int?>.from(inputMap) as T;
+      } else if (typeString.startsWith("Map<String, num?>")) {
+        return Map<String, num?>.from(inputMap) as T;
+      } else if (typeString.startsWith("Map<String, double?>")) {
+        return Map<String, double?>.from(inputMap) as T;
+      } else if (typeString.startsWith("Map<String, String?>")) {
+        return Map<String, String?>.from(inputMap) as T;
+      } else if (typeString.startsWith("Map<String, bool?>")) {
+        return Map<String, bool?>.from(inputMap) as T;
       }
     }
 
     return input as T;
-  } on CastError {
-    throw TypeCoercionException(T, input.runtimeType as Type);
   } on TypeError {
-    throw TypeCoercionException(T, input.runtimeType as Type);
+    throw TypeCoercionException(T, input.runtimeType);
   }
 }
diff --git a/lib/src/analyzer.dart b/lib/src/analyzer.dart
index 87be105..89c995f 100644
--- a/lib/src/analyzer.dart
+++ b/lib/src/analyzer.dart
@@ -20,13 +20,13 @@ class CodeAnalyzer {
     return getPath(uri);
   }
 
-  final Uri uri;
+  late final Uri uri;
 
-  AnalysisContextCollection contexts;
+  late AnalysisContextCollection contexts;
 
   Map<String, ResolvedUnitResult> _resolvedAsts = {};
 
-  Future<ResolvedUnitResult> resolveUnitAt(Uri uri) async {
+  Future<ResolvedUnitResult?> resolveUnitAt(Uri uri) async {
     for (var ctx in contexts.contexts) {
       final path = getPath(uri);
       if (_resolvedAsts.containsKey(path)) {
@@ -44,11 +44,11 @@ class CodeAnalyzer {
         "${contexts.contexts.map((c) => c.contextRoot.root.toUri()).join(", ")})");
   }
 
-  ClassDeclaration getClassFromFile(String className, Uri fileUri) {
+  ClassDeclaration? getClassFromFile(String className, Uri fileUri) {
     return _getFileAstRoot(fileUri)
         .declarations
-        .whereType<ClassDeclaration>()
-        .firstWhere((c) => c.name.name == className, orElse: () => null);
+        .whereType<ClassDeclaration?>()
+        .firstWhere((c) => c!.name.name == className, orElse: () => null);
   }
 
   List<ClassDeclaration> getSubclassesFromFile(
@@ -56,14 +56,14 @@ class CodeAnalyzer {
     return _getFileAstRoot(fileUri)
         .declarations
         .whereType<ClassDeclaration>()
-        .where((c) => c.extendsClause.superclass.name.name == superclassName)
+        .where((c) => c.extendsClause!.superclass.name.name == superclassName)
         .toList();
   }
 
   CompilationUnit _getFileAstRoot(Uri fileUri) {
     final path = getPath(fileUri);
     if (_resolvedAsts.containsKey(path)) {
-      return _resolvedAsts[path].unit;
+      return _resolvedAsts[path]!.unit!;
     }
 
     final unit = contexts.contextFor(path).currentSession.getParsedUnit(path);
diff --git a/lib/src/build.dart b/lib/src/build.dart
index 2d0b5e4..ebdb2d7 100644
--- a/lib/src/build.dart
+++ b/lib/src/build.dart
@@ -2,8 +2,10 @@ import 'dart:convert';
 import 'dart:io';
 import 'dart:mirrors';
 
-import 'package:runtime/runtime.dart';
 import 'package:runtime/src/build_context.dart';
+import 'package:runtime/src/compiler.dart';
+import 'package:runtime/src/file_system.dart';
+import 'package:runtime/src/generator.dart';
 
 class Build {
   Build(this.context);
@@ -11,21 +13,22 @@ class Build {
   final BuildContext context;
 
   Map<String, Uri> get packageMap => _packageMap ??= context.resolvedPackages;
-  Map<String, Uri> _packageMap;
+  Map<String, Uri>? _packageMap;
 
   Future execute() async {
     final compilers = context.context.compilers;
 
     print("Resolving ASTs...");
-    final astsToResolve = Set.from(compilers.expand((c) => c.getUrisToResolve(context)));
+    final astsToResolve =
+        Set.from(compilers.expand((c) => c.getUrisToResolve(context)));
     await Future.forEach(astsToResolve, (astUri) async {
-      await context.analyzer.resolveUnitAt(context.resolveUri(astUri));
+      await context.analyzer.resolveUnitAt(context.resolveUri(astUri as Uri)!);
     });
 
     print("Generating runtime...");
 
     final runtimeGenerator = RuntimeGenerator();
-    context.context.runtimes.map.forEach((typeName, runtime) {
+    context.context.runtimes?.map.forEach((typeName, runtime) {
       if (runtime is SourceCompiler) {
         runtimeGenerator.addRuntime(
             name: typeName, source: runtime.compile(context));
@@ -39,10 +42,10 @@ class Build {
     final pubspecMap = {
       'name': 'runtime_target',
       'version': '1.0.0',
-      'environment': {'sdk': '>=2.7.0 <3.0.0'},
+      'environment': {'sdk': '>=2.12.0-0 <3.0.0'},
       'dependency_overrides': {}
     };
-    Map overrides = pubspecMap['dependency_overrides'];
+    Map? overrides = pubspecMap['dependency_overrides'] as Map?;
     var sourcePackageIsCompiled = false;
 
     compilers.forEach((compiler) {
@@ -56,7 +59,7 @@ class Build {
       compiler.deflectPackage(Directory.fromUri(targetDirUri));
 
       if (packageInfo.name != nameOfPackageBeingCompiled) {
-        overrides[packageInfo.name] = {
+        overrides![packageInfo.name] = {
           "path": targetDirUri.toFilePath(windows: Platform.isWindows)
         };
       } else {
@@ -158,7 +161,7 @@ class Build {
   }
 
   _PackageInfo _getPackageInfoForCompiler(Compiler compiler) {
-    final compilerUri = reflect(compiler).type.location.sourceUri;
+    final compilerUri = reflect(compiler).type.location!.sourceUri;
     final parser = RegExp("package\:([^\/]+)");
     final parsed = parser.firstMatch(compilerUri.toString());
     if (parsed == null) {
@@ -167,7 +170,7 @@ class Build {
     }
 
     final packageName = parsed.group(1);
-    return _getPackageInfoForName(packageName);
+    return _getPackageInfoForName(packageName!);
   }
 }
 
diff --git a/lib/src/build_context.dart b/lib/src/build_context.dart
index 5953697..932b19c 100644
--- a/lib/src/build_context.dart
+++ b/lib/src/build_context.dart
@@ -2,18 +2,19 @@ import 'dart:io';
 import 'dart:mirrors';
 
 import 'package:analyzer/dart/ast/ast.dart';
-import 'package:pubspec_parse/pubspec_parse.dart';
+import 'package:pubspec/pubspec.dart';
 import 'package:runtime/src/analyzer.dart';
 import 'package:runtime/src/context.dart';
 import 'package:runtime/src/file_system.dart';
 import 'package:runtime/src/mirror_context.dart';
 import 'package:yaml/yaml.dart';
+import 'package:path/path.dart';
 
 /// Configuration and context values used during [Build.execute].
 class BuildContext {
   BuildContext(this.rootLibraryFileUri, this.buildDirectoryUri,
       this.executableUri, this.source,
-      {bool forTests})
+      {bool? forTests})
       : this.forTests = forTests ?? false {
     analyzer = CodeAnalyzer(sourceApplicationDirectory.uri);
   }
@@ -35,7 +36,7 @@ class BuildContext {
         'forTests': forTests
       };
 
-  CodeAnalyzer analyzer;
+  late CodeAnalyzer analyzer;
 
   /// A [Uri] to the library file of the application to be compiled.
   final Uri rootLibraryFileUri;
@@ -61,7 +62,7 @@ class BuildContext {
           .resolve("main_test.dart")
       : buildDirectoryUri.resolve("main.dart");
 
-  Pubspec get sourceApplicationPubspec => Pubspec.parse(
+  PubSpec get sourceApplicationPubspec => PubSpec.fromYamlString(
       File.fromUri(sourceApplicationDirectory.uri.resolve("pubspec.yaml"))
           .readAsStringSync());
 
@@ -117,16 +118,16 @@ class BuildContext {
     return file;
   }
 
-  Uri resolveUri(Uri uri) {
+  Uri? resolveUri(Uri? uri) {
     var outputUri = uri;
     if (outputUri?.scheme == "package") {
-      final segments = outputUri.pathSegments;
-      outputUri = resolvedPackages[segments.first].resolve("lib/");
+      final segments = outputUri!.pathSegments;
+      outputUri = resolvedPackages[segments.first]!.resolve("lib/");
       for (var i = 1; i < segments.length; i++) {
         if (i < segments.length - 1) {
-          outputUri = outputUri.resolve("${segments[i]}/");
+          outputUri = outputUri!.resolve("${segments[i]}/");
         } else {
-          outputUri = outputUri.resolve(segments[i]);
+          outputUri = outputUri!.resolve(segments[i]);
         }
       }
     } else if (outputUri != null && !outputUri.isAbsolute) {
@@ -137,7 +138,7 @@ class BuildContext {
   }
 
   List<String> getImportDirectives(
-      {Uri uri, String source, bool alsoImportOriginalFile = false}) {
+      {Uri? uri, String? source, bool alsoImportOriginalFile = false}) {
     if (uri != null && source != null) {
       throw ArgumentError(
           "either uri or source must be non-null, but not both");
@@ -154,15 +155,15 @@ class BuildContext {
     }
 
     var fileUri = resolveUri(uri);
-    final text = source ?? File.fromUri(fileUri).readAsStringSync();
+    final text = source ?? File.fromUri(fileUri!).readAsStringSync();
     final importRegex = RegExp("import [\\'\\\"]([^\\'\\\"]*)[\\'\\\"];");
 
     final imports = importRegex.allMatches(text).map((m) {
-      var importedUri = Uri.parse(m.group(1));
-      if (importedUri.scheme != "package" && !importedUri.isAbsolute) {
-        throw ArgumentError(
-            "Cannot resolve relative URIs in file located at $uri. "
-            "Replace imported URIs with package or absolute URIs");
+      var importedUri = Uri.parse(m.group(1)!);
+
+      if (!importedUri.isAbsolute) {
+        final path = fileUri!.resolve(importedUri.path);
+        return 'import \'file:${absolute(path.path)}\';';
       }
 
       return text.substring(m.start, m.end);
@@ -175,26 +176,26 @@ class BuildContext {
     return imports;
   }
 
-  ClassDeclaration getClassDeclarationFromType(Type type) {
+  ClassDeclaration? getClassDeclarationFromType(Type type) {
     final classMirror = reflectType(type);
     return analyzer.getClassFromFile(
         MirrorSystem.getName(classMirror.simpleName),
-        resolveUri(classMirror.location.sourceUri));
+        resolveUri(classMirror.location!.sourceUri)!);
   }
 
   List<Annotation> getAnnotationsFromField(Type _type, String propertyName) {
     var type = reflectClass(_type);
     var field =
-        getClassDeclarationFromType(type.reflectedType).getField(propertyName);
+        getClassDeclarationFromType(type.reflectedType)!.getField(propertyName);
     while (field == null) {
-      type = type.superclass;
+      type = type.superclass!;
       if (type.reflectedType == Object) {
         break;
       }
-      field = getClassDeclarationFromType(type.reflectedType)
+      field = getClassDeclarationFromType(type.reflectedType)!
           .getField(propertyName);
     }
 
-    return (field.parent.parent as FieldDeclaration).metadata.toList();
+    return (field!.parent!.parent as FieldDeclaration).metadata.toList();
   }
 }
diff --git a/lib/src/build_manager.dart b/lib/src/build_manager.dart
index 0d1a441..a75b1e9 100644
--- a/lib/src/build_manager.dart
+++ b/lib/src/build_manager.dart
@@ -1,7 +1,7 @@
 import 'dart:io';
 
 import 'package:analyzer/dart/ast/ast.dart';
-import 'package:isolate_executor/isolate_executor.dart';
+import 'package:conduit_isolate_exec/conduit_isolate_exec.dart';
 import 'package:runtime/runtime.dart';
 
 import 'build_context.dart';
@@ -11,7 +11,7 @@ class BuildExecutable extends Executable<Null> {
     context = BuildContext.fromMap(message);
   }
 
-  BuildContext context;
+  late BuildContext context;
 
   @override
   Future<Null> execute() async {
@@ -36,10 +36,8 @@ class BuildManager {
     // Here is where we need to provide a temporary copy of the script file with the main function stripped;
     // this is because when the RuntimeGenerator loads, it needs Mirror access to any declarations in this file
     var scriptSource = context.source;
-    final strippedScriptFile =
-        File.fromUri(context.targetScriptFileUri)
-          ..writeAsStringSync(scriptSource);
-
+    final strippedScriptFile = File.fromUri(context.targetScriptFileUri)
+      ..writeAsStringSync(scriptSource);
     final analyzer = CodeAnalyzer(strippedScriptFile.absolute.uri);
     final analyzerContext = analyzer.contexts.contextFor(analyzer.path);
     final mainFunctions = analyzerContext.currentSession
diff --git a/lib/src/compiler.dart b/lib/src/compiler.dart
index 1dbf802..1525cd2 100644
--- a/lib/src/compiler.dart
+++ b/lib/src/compiler.dart
@@ -18,9 +18,7 @@ abstract class Compiler {
   /// Returns a map of runtime objects that can be used at runtime while running in mirrored mode.
   Map<String, dynamic> compile(MirrorContext context);
 
-  void didFinishPackageGeneration(BuildContext context) {
-
-  }
+  void didFinishPackageGeneration(BuildContext context) {}
 
   List<Uri> getUrisToResolve(BuildContext context) => [];
 }
@@ -29,4 +27,4 @@ abstract class Compiler {
 abstract class SourceCompiler {
   /// The source code, including directives, that declare a class that is equivalent in behavior to this runtime.
   String compile(BuildContext ctx);
-}
\ No newline at end of file
+}
diff --git a/lib/src/context.dart b/lib/src/context.dart
index 1f18609..9a338e3 100644
--- a/lib/src/context.dart
+++ b/lib/src/context.dart
@@ -14,10 +14,10 @@ abstract class RuntimeContext {
     _current = runtime;
   }
 
-  static RuntimeContext _current;
+  static RuntimeContext? _current;
 
   /// The runtimes available to the executing application.
-  RuntimeCollection runtimes;
+  RuntimeCollection? runtimes;
 
   /// Gets a runtime object for [type].
   ///
@@ -30,7 +30,7 @@ abstract class RuntimeContext {
   /// In other words, if the type `Base` has a runtime and the type `Subclass` extends `Base`,
   /// `Subclass` must also have a runtime. The runtime objects for both `Subclass` and `Base`
   /// must be the same type.
-  dynamic operator [](Type type) => runtimes[type];
+  dynamic operator [](Type type) => runtimes?[type];
 
   T coerce<T>(dynamic input);
 }
diff --git a/lib/src/file_system.dart b/lib/src/file_system.dart
index 275089f..54d247d 100644
--- a/lib/src/file_system.dart
+++ b/lib/src/file_system.dart
@@ -1,11 +1,9 @@
 import 'dart:io';
 
-import 'package:meta/meta.dart';
-
 /// Recursively copies the contents of the directory at [src] to [dst].
 ///
 /// Creates directory at [dst] recursively if it doesn't exist.
-void copyDirectory({@required Uri src, @required Uri dst}) {
+void copyDirectory({required Uri src, required Uri dst}) {
   final srcDir = Directory.fromUri(src);
   final dstDir = Directory.fromUri(dst);
   if (!dstDir.existsSync()) {
@@ -30,7 +28,8 @@ void copyDirectory({@required Uri src, @required Uri dst}) {
 ///
 /// If locations on disk are relative Uris, they are resolved by [relativeTo]. [relativeTo] defaults
 /// to the CWD.
-Map<String, Uri> getResolvedPackageUris(Uri packagesFileUri, {Uri relativeTo}) {
+Map<String, Uri> getResolvedPackageUris(Uri packagesFileUri,
+    {Uri? relativeTo}) {
   relativeTo ??= Directory.current.uri;
 
   final packagesFile = File.fromUri(packagesFileUri);
@@ -53,7 +52,7 @@ Map<String, Uri> getResolvedPackageUris(Uri packagesFileUri, {Uri relativeTo}) {
 
     return MapEntry(
         packageName,
-        Directory.fromUri(relativeTo.resolveUri(uri).normalizePath())
+        Directory.fromUri(relativeTo!.resolveUri(uri).normalizePath())
             .parent
             .uri);
   }));
diff --git a/lib/src/generator.dart b/lib/src/generator.dart
index a246953..0435db6 100644
--- a/lib/src/generator.dart
+++ b/lib/src/generator.dart
@@ -1,15 +1,13 @@
 import 'dart:async';
 import 'dart:io';
 
-import 'package:meta/meta.dart';
-
 const String _directiveToken = "___DIRECTIVES___";
 const String _assignmentToken = "___ASSIGNMENTS___";
 
 class RuntimeGenerator {
   List<_RuntimeElement> _elements = [];
 
-  void addRuntime({@required String name, @required String source}) {
+  void addRuntime({required String name, required String source}) {
     _elements.add(_RuntimeElement(name, source));
   }
 
@@ -24,7 +22,8 @@ class RuntimeGenerator {
       srcDir.createSync(recursive: true);
     }
 
-    final libraryFile = File.fromUri(libDir.uri.resolve("generated_runtime.dart"));
+    final libraryFile =
+        File.fromUri(libDir.uri.resolve("generated_runtime.dart"));
     await libraryFile.writeAsString(loaderSource);
 
     final pubspecFile = File.fromUri(dir.uri.resolve("pubspec.yaml"));
@@ -46,7 +45,7 @@ description: A runtime generated by package:runtime
 version: 1.0.0
 
 environment:
-  sdk: '>=2.2.0 <3.0.0'  
+  sdk: '>=2.12.0-0 <3.0.0'  
 """;
 
   String get _loaderShell => """
@@ -67,15 +66,15 @@ class GeneratedContext extends RuntimeContext {
   
   @override 
   T coerce<T>(dynamic input) {
-    return runtime_cast.cast(input); 
+    return runtime_cast.cast<T>(input); 
   }
 }  
   """;
 
   String get loaderSource {
     return _loaderShell
-      .replaceFirst(_directiveToken, _directives)
-      .replaceFirst(_assignmentToken, _assignments);
+        .replaceFirst(_directiveToken, _directives)
+        .replaceFirst(_assignmentToken, _assignments);
   }
 
   String get _directives {
diff --git a/lib/src/mirror_coerce.dart b/lib/src/mirror_coerce.dart
index 74e4e8e..9f86302 100644
--- a/lib/src/mirror_coerce.dart
+++ b/lib/src/mirror_coerce.dart
@@ -4,7 +4,7 @@ import 'package:runtime/src/exceptions.dart';
 
 dynamic runtimeCast(dynamic object, TypeMirror intoType) {
   final exceptionToThrow =
-      TypeCoercionException(intoType.reflectedType, object.runtimeType as Type);
+      TypeCoercionException(intoType.reflectedType, object.runtimeType);
 
   try {
     final objectType = reflect(object).type;
@@ -18,7 +18,7 @@ dynamic runtimeCast(dynamic object, TypeMirror intoType) {
       }
 
       final elementType = intoType.typeArguments.first;
-      final elements = (object as List).map((e) => runtimeCast(e, elementType));
+      final elements = object.map((e) => runtimeCast(e, elementType));
       return (intoType as ClassMirror).newInstance(#from, [elements]).reflectee;
     } else if (intoType.isSubtypeOf(reflectType(Map, [String, dynamic]))) {
       if (object is! Map<String, dynamic>) {
@@ -28,15 +28,13 @@ dynamic runtimeCast(dynamic object, TypeMirror intoType) {
       final output = (intoType as ClassMirror)
           .newInstance(const Symbol(""), []).reflectee as Map<String, dynamic>;
       final valueType = intoType.typeArguments.last;
-      (object as Map<String, dynamic>).forEach((key, val) {
+      object.forEach((key, val) {
         output[key] = runtimeCast(val, valueType);
       });
       return output;
     }
   } on TypeError {
     throw exceptionToThrow;
-  } on CastError {
-    throw exceptionToThrow;
   } on TypeCoercionException {
     throw exceptionToThrow;
   }
diff --git a/lib/src/mirror_context.dart b/lib/src/mirror_context.dart
index 4cd8a9b..0fa6ada 100644
--- a/lib/src/mirror_context.dart
+++ b/lib/src/mirror_context.dart
@@ -65,9 +65,13 @@ class MirrorContext extends RuntimeContext {
   }
 }
 
-T firstMetadataOfType<T>(DeclarationMirror dm, {TypeMirror dynamicType}) {
+T? firstMetadataOfType<T>(DeclarationMirror dm, {TypeMirror? dynamicType}) {
   final tMirror = dynamicType ?? reflectType(T);
-  return dm.metadata
-      .firstWhere((im) => im.type.isSubtypeOf(tMirror), orElse: () => null)
-      ?.reflectee as T;
+  try {
+    return dm.metadata
+        .firstWhere((im) => im.type.isSubtypeOf(tMirror))
+        .reflectee;
+  } on StateError {
+    return null;
+  }
 }
diff --git a/pubspec.yaml b/pubspec.yaml
index 4449af4..735ac69 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -5,17 +5,17 @@ author: Joe Conway <joe.conway@stablekernel.com>
 homepage: https://stablekernel.com
 
 environment:
-  sdk: '>=2.2.0 <3.0.0'
+  sdk: '>=2.12.0-0 <3.0.0'
 
 dependencies:
-  analyzer: '>=0.32.0 <0.50.0'
-  args: ^1.5.0
-  pubspec_parse: '>=0.1.4 <1.0.0'
-  isolate_executor: ^2.0.0
-  meta: ^1.1.5
-  yaml: ^2.1.15
+  analyzer: ^1.2.0
+  args: ^2.0.0
+  pubspec: ^2.0.1
+  conduit_isolate_exec: ^1.0.0-b1
+  yaml: ^3.1.0
 
 dev_dependencies:
-  pedantic: ^1.0.0
-  test: ^1.0.0
-  command_line_agent: ^1.0.0-b1
\ No newline at end of file
+  pedantic: ^1.11.0
+  test: ^1.16.5
+  command_line_agent:
+    git: https://github.com/j4qfrost/dart-test-terminal
\ No newline at end of file
diff --git a/test/coerce_test.dart b/test/coerce_test.dart
index 66c0fdf..be5dcaa 100644
--- a/test/coerce_test.dart
+++ b/test/coerce_test.dart
@@ -15,7 +15,8 @@ void main() {
     return cast<T>(input);
   };
 
-  final testInvocation = (String suiteName, T Function<T>(dynamic input) coerce) {
+  final testInvocation =
+      (String suiteName, T? Function<T>(dynamic input) coerce) {
     group("($suiteName) Primitive Types (success)", () {
       test("dynamic", () {
         final x = coerce<dynamic>(wash("foo"));
@@ -26,22 +27,22 @@ void main() {
         final x = coerce<int>(wash(2));
         expect(x, 2);
 
-        expect(coerce<int>(null), null);
+        expect(coerce<int?>(null), null);
       });
       test("String", () {
         final x = coerce<String>(wash("string"));
         expect(x, "string");
-        expect(coerce<String>(null), null);
+        expect(coerce<String?>(null), null);
       });
       test("bool", () {
         final x = coerce<bool>(wash(true));
         expect(x, true);
-        expect(coerce<bool>(null), null);
+        expect(coerce<bool?>(null), null);
       });
       test("num", () {
         final x = coerce<num>(wash(3.2));
         expect(x, 3.2);
-        expect(coerce<num>(null), null);
+        expect(coerce<num?>(null), null);
 
         final y = coerce<int>(wash(3));
         expect(y, 3);
@@ -49,7 +50,7 @@ void main() {
       test("double", () {
         final x = coerce<double>(wash(3.2));
         expect(x, 3.2);
-        expect(coerce<double>(null), null);
+        expect(coerce<double?>(null), null);
       });
     });
 
@@ -103,50 +104,50 @@ void main() {
 
     group("($suiteName) List Types (success)", () {
       test("null/empty", () {
-        List<String> x = coerce<List<String>>(null);
+        List<String>? x = coerce<List<String>?>(null);
         expect(x, null);
 
-        x = coerce<List<String>>([]);
+        x = coerce<List<String>>([])!;
         expect(x, []);
       });
 
       test("int", () {
-        List<int> x = coerce<List<int>>(wash([2, 4]));
+        List<int> x = coerce<List<int>>(wash([2, 4]))!;
         expect(x, [2, 4]);
       });
 
       test("String", () {
-        List<String> x = coerce<List<String>>(wash(["a", "b", "c"]));
+        List<String> x = coerce<List<String>>(wash(["a", "b", "c"]))!;
         expect(x, ["a", "b", "c"]);
       });
 
       test("num", () {
-        List<num> x = coerce<List<num>>(wash([3.0, 2]));
+        List<num> x = coerce<List<num>>(wash([3.0, 2]))!;
         expect(x, [3.0, 2]);
       });
 
       test("bool", () {
-        List<bool> x = coerce<List<bool>>(wash([false, true]));
+        List<bool> x = coerce<List<bool>>(wash([false, true]))!;
         expect(x, [false, true]);
       });
 
-
       test("list of map", () {
-        List<Map<String, dynamic>> x = coerce<List<Map<String, dynamic>>>(wash([
+        List<Map<String, dynamic>?> x =
+            coerce<List<Map<String, dynamic>?>>(wash([
           {"a": "b"},
           null,
           {"a": 1}
-        ]));
+        ]))!;
         expect(x, [
           {"a": "b"},
           null,
           {"a": 1}
         ]);
 
-        expect(coerce<List<Map<String, dynamic>>>(null), null);
-        expect(coerce<List<Map<String, dynamic>>>([]), <Map<String, dynamic>>[]);
+        expect(coerce<List<Map<String, dynamic>>?>(null), null);
+        expect(
+            coerce<List<Map<String, dynamic>>>([]), <Map<String, dynamic>>[]);
       });
-
     });
 
     group("($suiteName) List Types (cast error)", () {
@@ -199,28 +200,30 @@ void main() {
 
     group("($suiteName) Map types (success)", () {
       test("null", () {
-        Map<String, dynamic> x = coerce<Map<String, dynamic>>(null);
+        Map<String, dynamic>? x = coerce<Map<String, dynamic>?>(null);
         expect(x, null);
       });
 
       test("string->dynamic", () {
         Map<String, dynamic> x =
-            coerce<Map<String, dynamic>>(wash({"a": 1, "b": "c"}));
+            coerce<Map<String, dynamic>>(wash({"a": 1, "b": "c"}))!;
         expect(x, {"a": 1, "b": "c"});
       });
 
       test("string->int", () {
-        Map<String, int> x = coerce<Map<String, int>>(wash({"a": 1, "b": 2}));
+        Map<String, int> x = coerce<Map<String, int>>(wash({"a": 1, "b": 2}))!;
         expect(x, {"a": 1, "b": 2});
       });
 
       test("string->num", () {
-        Map<String, num> x = coerce<Map<String, num>>(wash({"a": 1, "b": 2.0}));
+        Map<String, num> x =
+            coerce<Map<String, num>>(wash({"a": 1, "b": 2.0}))!;
         expect(x, {"a": 1, "b": 2.0});
       });
 
       test("string->string", () {
-        Map<String, String> x = coerce<Map<String, String>>(wash({"a": "1", "b": "2.0"}));
+        Map<String, String> x =
+            coerce<Map<String, String>>(wash({"a": "1", "b": "2.0"}))!;
         expect(x, {"a": "1", "b": "2.0"});
       });
     });
diff --git a/test/context_test.dart b/test/context_test.dart
index f94c2cf..29cf23d 100644
--- a/test/context_test.dart
+++ b/test/context_test.dart
@@ -10,7 +10,7 @@ void main() {
       .resolve("application/")
       .resolve("lib/")
       .toFilePath();
-  BuildContext ctx;
+  late BuildContext ctx;
 
   setUpAll(() async {
     final cmd = Platform.isWindows ? "pub.bat" : "pub";
diff --git a/test/project_analyzer_test.dart b/test/project_analyzer_test.dart
index 2af6512..0203d14 100644
--- a/test/project_analyzer_test.dart
+++ b/test/project_analyzer_test.dart
@@ -18,7 +18,7 @@ void main() {
     final klass = p.getClassFromFile("ConsumerSubclass",
         terminal.libraryDirectory.absolute.uri.resolve("application.dart"));
     expect(klass, isNotNull);
-    expect(klass.name.name, "ConsumerSubclass");
-    expect(klass.extendsClause.superclass.name.name, "Consumer");
+    expect(klass!.name.name, "ConsumerSubclass");
+    expect(klass.extendsClause!.superclass.name.name, "Consumer");
   });
 }
diff --git a/test/test_packages/application/pubspec.yaml b/test/test_packages/application/pubspec.yaml
index 11a9bca..7cf361c 100644
--- a/test/test_packages/application/pubspec.yaml
+++ b/test/test_packages/application/pubspec.yaml
@@ -3,13 +3,13 @@ description: A starting point for Dart libraries or applications.
 version: 1.0.0
 
 environment:
-  sdk: '>=2.2.0 <3.0.0'
+  sdk: '>=2.12.0-0 <3.0.0'
 
 dependencies:
-  meta: ^1.0.0
+  meta: ^1.3.0
   dependency:
     path: ../dependency/
 
 dev_dependencies:
-  pedantic: ^1.0.0
-  test: ^1.0.0
+  pedantic: ^1.11.0
+  test: ^1.16.5
diff --git a/test/test_packages/dependency/pubspec.yaml b/test/test_packages/dependency/pubspec.yaml
index 0085740..cff8604 100644
--- a/test/test_packages/dependency/pubspec.yaml
+++ b/test/test_packages/dependency/pubspec.yaml
@@ -3,12 +3,12 @@ description: A starting point for Dart libraries or applications.
 version: 1.0.0
 
 environment:
-  sdk: '>=2.2.0 <3.0.0'
+  sdk: '>=2.12.0-0 <3.0.0'
 
 dependencies:
   runtime:
     path: ../../..
 
 dev_dependencies:
-  pedantic: ^1.0.0
-  test: ^1.0.0
+  pedantic: ^1.11.0
+  test: ^1.16.5