MERN Starter Kit: Error reporting is inconsistent

[ramya-rao-a]

Test tour MERN - #22277

• VSCode Version: Insiders
• OS Version: Mac

Steps to Reproduce:

1. Open index.js, change any of the require to require123 : No error
2. Open index.js, add boohoo() anywhere : No error
3. Open server.js, change console.error to console.errr : No error
4. Open server.js, add boohoo() anywhere : Error shown: eslint: boohoo is not defined
5. Open server.js, change dummyData() to dummyDta(): Error shown: eslint: dummyDta is not defined
6. Open post.controller.js, change Post.find() to Post.fin(): No error

Also, npm run build doesn't find any of these errors.

Meaning if there was a typo, user wouldn't know until the program is run.

[mjbvz]

Since the errors are coming from ESLint here, would this issue be with that extension instead of with our core js/ts support? Perhaps it just needs to be configured correctly to report errors in all cases?

The checkJS flag in TS 2.3.1 may also be interesting to try out on these files

[mjbvz]

Verified that all of these are now reported as errors by adding // @ts-check to the file or setting "javascript.implicitProjectConfig.checkJs": true