Termination of big simulations sometimes failes

Summary

(Summarize the bug encountered concisely)

Steps to Reproduce

Run project 'Neue Regelstrategie/01 Referenzszenario' on branch us6362_*, wait until the simulation runs and then abort it.

Expected Behavior

Simulation termination succeeds

Actual Behaviour

During termination process the following error occurs:

Monolith "plc_monolith_Network_Controller" (ID 450, type "PLC") of 'ScenarioSchemaBasic(project_id=1, id=1, name='01 Referenzszenario', project_name='Neue Regelstrategie', folder_path=PosixPath('IW3/IWM'), variant_name='project')' terminated.
Exception in thread Handling element termination:
Traceback (most recent call last):
  File "/home/philip/jarvis/distribution.py", line 1290, in handle_termination
    self.join_element(
  File "/home/philip/jarvis/distribution.py", line 1328, in join_element
    element: InstantiatedElement = DBSession.scalars(
  File "/home/philip/jarvis/.venv/lib/python3.8/site-packages/sqlalchemy/engine/result.py", line 1522, in one
    return self._only_one_row(
  File "/home/philip/jarvis/.venv/lib/python3.8/site-packages/sqlalchemy/engine/result.py", line 562, in _only_one_row
    raise exc.NoResultFound(
sqlalchemy.exc.NoResultFound: No row was found when one was required

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/home/philip/.pyenv/versions/3.8.6/lib/python3.8/threading.py", line 932, in _bootstrap_inner
    self.run()
  File "/home/philip/.pyenv/versions/3.8.6/lib/python3.8/threading.py", line 870, in run
    self._target(*self._args, **self._kwargs)
  File "/home/philip/jarvis/distribution.py", line 1316, in handle_termination
    raise errors.MarkError("Unexpected error while listening for simulation data.") from e
errors.MarkError: Unexpected error while listening for simulation data.

The mark process crashes and needs to be restarted manually (so the GUI).