RuntimeError during realtime simulation

[milosz275]

There is a bug over concurrent class member access when running the app in the realtime, even though mutex is being used.
Error:

Traceback (most recent call last):
File "/home/mlsh/uksw/uav-collision-avoidance/uav_collision_avoidance/src/simulation/simulation_widget.py", line 499, in paintEvent
self.draw_destinations(aircraft, scale)
File "/home/mlsh/uksw/uav-collision-avoidance/uav_collision_avoidance/src/simulation/simulation_widget.py", line 217, in draw_destinations
for idx, destination in enumerate(self.__aircraft_fccs[aircraft.aircraft_id].destinations):
RuntimeError: deque mutated during iteration