Thank you again for reporting this issue, and for providing that additional info! I'll be making some time to start digging into this tomorrow.
If you use discord, could you please join the Jadeus Games server? Depending on what I find, I may request a copy of a crash log or try sending you an experimental build of the game to determine whether the crash is fixed.
I also wanted to say thank you for playing Bewildebots, and congrats for having completed so many of the puzzles so far!
EDIT: Could you please download and try the [EXPERIMENTAL] Bewildebots_1.4_Windows.zip build? The only real change here is an upgrade to the Unity version used to build the game. The likelihood that this resolves the issue seems low to me, but it is the quickest and easiest potential fix to test.
I'd like to be completely transparent in letting you know I am not able to reproduce the crash myself with the build you are using currently (I no longer have a Windows 7 PC), so attempting to find a fix for this specific crash may be a challenge. . I'm more than happy to work with you on a resolution though, if you don't mind my requesting you download and test experimental builds. I'm very sorry again that you are experiencing this issue!