"File name X differs from Y only in casing." problem when using webpack style path alias

Type: Bug

I am using webpack-style path aliases for Javascript imports. For example:

import { Pricing } from 'SRC/pricing.mjs';

with a jsconfig.json that looks like this:

{
    "compilerOptions": {
      "module": "es6",
      "target": "es6",
    },
    "baseUrl": ".",
    "paths": {
      "SRC/*": ["./src/*"]
    }
}

With the result that SRC/pricing.mjs is replaced with {baseurl}/src/pricing.mjs no matter what directory the importing code lives in.

This works fine, however I get warnings like the following in the 'Problems' view:

File name '<path to project>/SRC/pricing.mjs' differs from already included file name '<path to project>/src/pricing.mjs' only in casing.
  The file is in the program because:
    Matched by default include pattern '**/*'
    Imported via 'SRC/pricing.mjs' from file '<path to project>/src/page/index-client.js'
    Imported via 'SRC/pricing.mjs' from file '<path to project>/src/page/index-html.js'
    Imported via 'SRC/pricing.mjs' from file '<path to project>/src/page/pricing-calculator-client.js'
    Imported via 'SRC/pricing.mjs' from file '<path to project>/src/page/pricing-calculator-html.js'

I think the code that checks for case insensitivity issues might not be fully / correctly aware of how jsconfig.son path aliases work.

I can workaround the issue by adding "forceConsistentCasingInFileNames": false to compilerOptions however then I don't get the general benefit of this problem detection.

If I use SRC2 or $SRC instead of SRC everything is fine.

VS Code version: Code 1.77.3 (Universal) (704ed70d4fd1c6bd6342c436f1ede30d1cff4710, 2023-04-12T09:19:37.325Z)
OS version: Darwin arm64 22.4.0
Modes:
Sandboxed: Yes

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Start by reproducing the diagnostic with the shown jsconfig.json and the SRC/pricing.mjs imports. Compare how the aliased path and the real src/pricing.mjs path are reported, while keeping forceConsistentCasingInFileNames enabled. Done means valid webpack-style aliases no longer produce a casing warning, without disabling general casing checks.