Fix npm install error on Windows (spawn EINVAL) (#1203)

[kristavlastou]

Resolved an issue where spawn('npm', ['install']) failed on Windows due to npm being a batch script.

• Updated Kernel.js to determine the correct npm command based on the OS.
• Now uses npm.cmd on Windows and npm otherwise.

This ensures npm install runs correctly across all operating systems.

[CLAassistant]

All committers have signed the CLA.

[kristavlastou]

Thank you for your feedback but I cannot spot the duplicated proc declaration as I declare it only in line 403 as I modified only 2 lines in the function. Also Vscode also doesn't point out any Syntax error. Can you explain it further?

[KernelDeimos]

@DarkCodeStudios is it possible you misinterpreted the diff? I don't see a duplication declaration either.