Looks like this was first spotted by bendbob last night. Easy to reproduce. If you are running a script/shaking/wiggling and attempt to make a new track or change tracks fold.it will crash throwing into the log:

ERROR: !is_tool_thread_running()
ERROR:: Exit from: /scratch/scooper/src/mini-interactive-main/mini/src/game/application/novice/NoviceGame.cc line: 7356

It's the good old "trying to do something while it's already doing something else" bug. May need to grey out and prevent changing tracks during an action or have it stop its current task and then switch.