Updates to nix shell script

[arrowmaster]

Multiple updates to the nix run.sh mostly to correct for observed issues from users.

1. Add set -e to halt on any unexpected errors

At least one issue was observed where the file command was not available on a users system. An error was thrown but the script continued and threw more errors. Now it will just stop on any unexpected errors.
#91

2. Add error and exit when Windows executable is detected

This was included in the BepInEx 6 branch some time ago but never made it into upstream and back to BepInEx 5 or other branches. This is an extremely common user error that will now get a correct error message.

3. Allow the rare usage of Steam launching a shell script

There are a few rare games on Steam where the developers call a shell script instead of a binary. They might not work with this change but it at least provide a boilerplate spot for more game specific changes to be placed if needed.

4. Change Steam executable detection to a simpler check for a file located in the working directory

My original solution for a way that did not require executable_name to be set was overly complicated and depended on game executables having the default file extensions from Unity. This solution simply looks for an argument that has a matching prefix with the working directory. Before launching a game, Steam sets the working directory to the game directory then launches the executable in the game directory by absolute path.

[Copilot]

Pull request overview

This pull request updates the Unix/Linux shell script (run.sh) to address several user-reported issues and improve error handling. The changes focus on making the script more robust and providing better feedback when errors occur.

Changes:

• Added set -e to halt execution on unexpected errors, preventing cascading failures
• Simplified Steam executable detection by checking if arguments are prefixed with the working directory path
• Added explicit detection and error messaging for Windows PE32 executables
• Added fallback support for games that launch shell scripts instead of binaries

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[toebeann]

LGTM