Hi there, what Operating System are you running the game on? Are you using the mod launcher? - If so, could you download and put this hack inside your "Hacks" folder? If you don't have it, create one (right next to mods). Let me know if this helps!

Thank you so much, I've been trying to solve the error for hours.

Hi there, what Operating System are you running the game on? Are you using the mod launcher? - If so, could you download and put this hack inside your "Hacks" folder? If you don't have it, create one (right next to mods). Let me know if this helps!

Meshes and collisions are separated from one another
If you want to make a certain part invisible - delete the mesh, or edit it in blender, or change it's texture to an empty PNG file
Alternatively, utilizing ASF, you can hide specific vehicle meshes under specific conditions without deleting anything, more on that here

well, i use avast premium.
I was already suspecting it was my antivirus

says: "Lucas Simpsons Hit & Run Launcher.exe will be compressed only after closing the application using it. Modifications will be lost if you close WinRAR before that "

Based on my tests, that's what WinRAR says if a file, opened from within an archive, is deleted (from the temporary location WinRAR extracts it to, to run it), so it sounds like, in both cases, the executable is getting deleted. The executable unexpectedly getting deleted sounds to me like a false-positive in your antivirus software, causing it to delete it.

According to VirusTotal, none of the antivirus software, it supports, currently considers version 1.24 of the Mod Launcher a virus:
www.virustotal.com/gui/file/f5cb0903c732ab9c2fead01d9d13e546e15cdeacf52270fbe076c0751a7a1c5a/detection
www.virustotal.com/gui/file/cd2ae0b729195effa5f778413fd06c19fc499066c0309c809d103aa634657ff9/detection

What antivirus software do you use?

Yours sincerely,
Lucas Cardellini

yes, the mod launcher is deleted

this only happened with version 1.24

the mod launcher disappears

Do you mean the Mod Launcher executable file (Lucas Simpsons Hit & Run Mod Launcher.exe) is deleted or its window closes?

And can you please confirm the exact version you were having the issue with? Was it 1.24 (currently the newest version) or another version?

Yours sincerely,
Lucas Cardellini

I managed to make it work, I went down to the previous version