When you thrown your last rock in challenge mode, such that the rock gets deleted before stopping, here are some errors:
ERROR: connect: Signal 'tree_exiting' is already connected to given method '_on_delete' in that object.
At: core/object.cpp:1515.
ERROR: connect: Signal 'stopped_or_deleted' is already connected to given method '_last_rock_stopped_or_gone' in that object.
At: core/object.cpp:1515.
When you thrown your last rock in challenge mode, such that the rock gets deleted before stopping, here are some errors: