Hey R0jo, I'm still battling that one issue I encountered earlier, and it is quite weird since it only happens in certain levels.
I have had some difficulty in pinpointing the problem, but now I will scrap rest of my game and try to gather just bare bones version for demonstrating the error.. it happens when you make joints between sprites, and then one sprite's frame has been changed on the fly and it undergoes several collisions. Attached below is what I get in the console:
Uncaught TypeError: Cannot read property 'parent' of undefined
subtreeRemove rojoChipmunkBeta_behavior.js:2378
BBTree.remove rojoChipmunkBeta_behavior.js:2519
Space.removeStaticShape rojoChipmunkBeta_behavior.js:3961
Space.removeShape rojoChipmunkBeta_behavior.js:3912
behinstProto.updateShape rojoChipmunkBeta_behavior.js:6710
behinstProto.changeShapeCheck rojoChipmunkBeta_behavior.js:7016
behinstProto.tick rojoChipmunkBeta_behavior.js:7056
Runtime.logic preview.js:2303
Runtime.tick preview.js:2056tickFunc
.capx to be followed as soon as I manage to strip it =)