fix source map of modules beyond entry

[xania]

Description

This small update fixes source map of modules beyond entry files. I am on windows machine but I dont belief it matters in this case.
Url's at this point start with '/' which is not valid in ssr mode, causing an error in VSCode:

[UriError]: If a URI does not contain an authority component, then the path cannot begin with two slash characters ("//")

Additional context

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What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

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[sapphi-red]

@xania Do you have a reproduction? I want to check what is wrong here.

[xania]

@xania Do you have a reproduction? I want to check what is wrong here.

It seems like it's fixed in this branch. I tried to reproduce it a clean empty project and also in my day to day project but likely could not find any issues.