Normally you can check the log file located in the AppData, next to where you put the mod folders. (on Windows: %appdata%/Strive/logs)
If it's empty after the game closes, then I'd recommend trying the Debug mod(https://itch.io/t/1137280/debugmod-v1) and checking the second window for errors.
Edit: if you are changing the code yourself, then it will be tricky to help.