You are not the only one. Almost anyone programming games or programming anything ecounters such problems from time to time.

When you know that the problem is your level and not your script, the next logical step is starting only your bare .wmb level without any script or entities. For this you can just move the .wmb file into a separate folder. If it then still crashes, it's something in the wmb file. It's then probably a damaged texture file or something like that.