ERROR : root : 'NoneType' object is not subscriptable
Traceback (most recent call last):
File "/Users/brian/git/mpf/mpf/commands/core.py", line 130, in __init__
MachineController(mpf_path, machine_path, vars(args)).run()
File "/Users/brian/git/mpf/mpf/core/machine.py", line 554, in run
self._run_loop()
File "/Users/brian/git/mpf/mpf/core/machine.py", line 575, in _run_loop
self.process_frame()
File "/Users/brian/git/mpf/mpf/core/machine.py", line 590, in process_frame
self.events.process_event_queue()
File "/Users/brian/git/mpf/mpf/core/events.py", line 477, in process_event_queue
**event[3])
File "/Users/brian/git/mpf/mpf/core/events.py", line 412, in _process_event
result = handler[0](**merged_kwargs)
File "/Users/brian/git/mpf/mpf/core/device_manager.py", line 219, in _control_event_handler
callback(mode=mode)
File "/Users/brian/git/mpf/mpf/devices/shot_group.py", line 288, in rotate_left
self.rotate(direction='left', mode=mode)
File "/Users/brian/git/mpf/mpf/devices/shot_group.py", line 235, in rotate
'player_variable']],
TypeError: 'NoneType' object is not subscriptable
config: