fix(core): fix bytecode cache index generation error

[nabetti1720]

Issue # (if available)

fix #846

Description of changes

There was an error in the index generation process for the bytecode cache.
Specifically, the index was generated in a format different from the chunk file name written in the code (specifically, the extension was missing), which caused a resolution error.

Checklist

• Created unit tests in tests/unit and/or in Rust for my feature if needed
• Ran make fix to format JS and apply Clippy auto fixes
• Made sure my code didn't add any additional warnings: make check
• Added relevant type info in types/ directory
• Updated documentation if needed (API.md/README.md/Other)

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[richarddavison]

Nice finding. Thank you!