build combination dict geeft error
Traceback (most recent call last): File "C:\Users\biers004\AppData\Local\mambaforge\envs\combiner\Lib\site-packages\prefect\engine\task_runner.py", line 880, in get_task_run_state value = prefect.utilities.executors.run_task_with_timeout( ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "C:\Users\biers004\AppData\Local\mambaforge\envs\combiner\Lib\site-packages\prefect\utilities\executors.py", line 468, in run_task_with_timeout return task.run(*args, **kwargs) # type: ignore ^^^^^^^^^^^^^^^^^^^^^^^^^ File "f:\combiner\src\combinations.py", line 88, in build_combination_dict u_combis.update(list(d.keys())) ^^^^^^ AttributeError: 'NoneType' object has no attribute 'keys'