in my opinion this is caused by Worker class which after deleting Widget has reference to that deleted Widget iterator and it tries to change it. Solution is to delete also this iterator.
[x] Problem solved
[x] Add popup to prompt user that this action will restart simulation
[x] Force the same fix when user want's to add new Plot during animation
When widget is deleted crash occur:
in my opinion this is caused by Worker class which after deleting Widget has reference to that deleted Widget iterator and it tries to change it. Solution is to delete also this iterator.