Opening custom rig crashes my game

Help and Feedback Art Design Support
#1

I’m trying to make a robot arm and it crashes when I open it in animation editor? Not sure why

(the things inside the parts are Motor6Ds)

Screen Shot 2021-12-04 at 2.36.50 PM

#2

Is the Robot Arm a character? Why does it have a humanoid inside?

#3

Its a robot arm I want to animate not sure how to do it without humanoids