Damn it. Thanks so much for letting me know. I just changed the way the save function works and tested it after wiping the save files completely from the appdata folder, it should be in working order now.
I hate to ask, but is it possible you could download it again and see if the crash happens? Just the first mission.
I only beat the first level since I didn't want to repeat content, but the stacked munition launcher is insanely OP at fighting from a defensive position and minimizing collateral
It really is OP, haha. I'll need to figure out some ways to balance it aside from just making it a late-game weapon.