Closed phet-steele closed 7 years ago
This was occurring during fuzz testing. As best I can tell, fuzz testing could create a race condition where a coin term was added or removed from an expression and the expression animated to the point where it joined another expression all during a single step. I tried for a while and couldn't duplicate it manually, but I was able to duplicate during fuzz testing and examine the state of the code. By moving the animation to the end of the step function, race conditions such as this can be avoided because the coin terms won't have been removed when the animation is stepped. So, this should be fixed. Back to @phet-steele to verify on master.
By the way, this was introduced recently when the TWEEN animations were replaced, see #39.
Bayes has not been reporting the error, we should be good here!