GUI crashes when skill manager is restarted while a skill is running and a new skill is started afterwards

[matthias-mayr]

When restarting the skill manager while a skill is running, the GUI crashes when starting the first skill after the skill manager becomes online again:

Traceback (most recent call last):
  File "/home/matthias/Workspaces/skiros2_ws/build/skiros2_gui/skiros2_gui/core/skiros_widget.py", line 1331, in on_skill_exe_button_clicked
    if self._sli.agent.execute(execution_id=self._sli.agent.task):
  File "/home/matthias/Workspaces/skiros2_ws/build/skiros2_skill/skiros2_skill/ros/skill_manager_interface.py", line 42, in task
    return self.tasks[0]
IndexError: list index out of range