chore: Add image validation for Gatsby components and enhance error handling

[leecalcote]

Signed-off-by: Lee Calcote lee.calcote@layer5.io

Description

A new make target: check-images reports if any <GatsbyImage /> lacking an explicit image prop (exit code 1 when issues are found).

To narrow the scan to a folder with make check-images -- src/pages/community. This script is useful as a guardrail.

[saurabhraghuvanshii]

Build failing

[leecalcote]

Build failing

Clearly, it is. This sort of feedback isn't helpful.

[Fireentity]

This build is probably failing because of a function called before its definition. I'm trying to check if this is true

[Fireentity]

The modifications are causing the build to fail, even after the corrections I suggested, with the following error:

ERROR  UNKNOWN

Truncated page data information for the failed page "/learn/learning-paths/mastering-service-meshes-for-developers/introduction-to-service-meshes/istio/deploy-an-application": {

 "errors": {},
 "path": "/learn/learning-paths/mastering-service-meshes-for-developers/introduction-to-service-meshes/istio/deploy-an-application",
 "slicesMap": {},
 "pageContext": {
   "learnpath": "mastering-service-meshes-for-developers",
   "slug": "learn/learning-paths/mastering-service-meshes-for-developers/introduction-to-service-meshes/istio/deploy-an-application",
   "course": "introduction-to-service-meshes",
   "section": "istio",
   "chapter": "deploy-an-application",
   "pageType": "chapter",
   "frontmatter": {
     "docType": "Chapter",
     "chapterTitle": "Deploy a sample application",
     "description": "Meshery, collaborative Kubernetes manager",
     "videos": 4,
     "lectures": 12,
     "order": 2

   }
 }
}

failed Building static HTML for pages - 3.027s

ERROR #95313  HTML.COMPILATION

Building static HTML failed for path "/learn/learning-paths/mastering-service-meshes-for-developers/introduction-to-service-meshes/istio/deploy-an-application"

See our docs page for more info on this error: https://gatsby.dev/debug-html

 WebpackError: [Chapters] Missing meshesYouLearn image data for: istio, linkerd (chapter: learn/learning-paths/mastering-service-meshes-for-developers/introduction-to-service-meshes/istio/deploy-an-application).

This error is caused by the absence of meshesYouLearn in the frontmatter of some files. While some items in the content-learn folder clearly have the field, others do not. This might be intended (implying we want to add that information there as well), or it might be an error.

[leecalcote]

@Fireentity's code change suggestions have been applied. This branch is now sync'ed with master.