Can you post the shareable error report logs or a screencap of the report code? The Dev needs that to figure out what caused the crash.
So no error reports/crash logs are generated? You don't get any error message appearing when the invalid states break the game? In that case, are you using the most recent public build and what OS are you using? That could help isolate the issue if it's not possible to replicate for the dev on their own system.