Better error when unknown integrator is passed to md

Author: bernstei

wfl/generate/md/__init__.py

@@ -306,7 +306,8 @@ def process_step(interval):
 
 
 def _sample_autopara_wrappable_kwargs(atoms, calculator, steps, dt, **kwargs):
-    assert kwargs.get("integrator", "Berendsen") in ["Berendsen", "Langevin", "LangevinBAOAB"]
+    if kwargs.get("integrator", "Berendsen") not in ["Berendsen", "Langevin", "LangevinBAOAB"]:
+        raise ValueError(f"Unknown integrator {kwargs['integrator']}, not Berendsen, Langevin, or LangevinBAOAB")
 
     calculator = construct_calculator_picklesafe(calculator)