Box2d b2DynamicTree assertion

[Bencepapa]

I'm working on a table but started to get Box2d assertion here and there while playing.

I attached my field in json
bencepapa.zip

Assert:
java: ./Box2D/Collision/b2DynamicTree.h:164: const b2AABB& b2DynamicTree::GetFatAABB(int32) const: Assertion 0 <= proxyId && proxyId < m_nodeCapacity' failed.

Process finished with exit code 134 (interrupted by signal 6: SIGABRT)
`
I play the game in the editor and gets this assert allways after Game Over (all the three bals are killed) or when I stop the game.
Last thing I added is the grey line at the bottom to kill the falling ball.

[Bencepapa]

Solved it (kind of):
If I comment out all the code about rightBallLock variable in the script, the game works (can Stop the game without crash).