fix: address file path mismatch when loading Vite config file on Windows (fix #12923)

[fwouts]

Description

This is a fix for #12923.

Optimisations in #12553 caused a regression on Windows, where on some systems the Vite config file path has a different casing than the file path passed by the Node.js loader in require.extensions, causing the equality check to fail.

Additional context

This appears not to be reproducible on GitHub CI, perhaps because the bug only occurs when the file system is case sensitive or not?

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What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

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[nickturrietta]

@fwouts Do you think this should also fix the #12553 regression for those of us on Windows with mapped local drives?

Ex. W:\myapp\vite.config.js => C:\websites\myapp\vite.config.js

In my case, since the bug was introduced, npm run build does not work in this folder W:\myapp but it works in the target folder C:\websites\myapp

[fwouts]

@fwouts Do you think this should also fix the #12553 regression for those of us on Windows with mapped local drives?

Ex. W:\myapp\vite.config.js => C:\websites\myapp\vite.config.js

In my case, since the bug was introduced, npm run build does not work in this folder W:\myapp but it works in the target folder C:\websites\myapp

It's possible yes, do you have a stack trace to share?

[nickturrietta]

@fwouts It's working fine in the target folder. But this is what I see in the local mapped drive.

[fwouts]

@nickturrietta yes, this PR should fix that.

[bluwy]

The fix sounds good to me. I'm guessing node uses fs.realpath internally too so make sense to align the usage.