Elections: deletion error

[MSoeb]

Describe the bug
Currently an election with at least one candidate and the final state 'finished' can't be deleted. Error message with 'Error: It is not permitted to remove a candidate from a finished assignment!' appears.

How to Reproduce
Steps to reproduce the behavior:

1. open a meeting
2. open elections
3. create an election
4. add a candidate and change the state to 'finished'. -> try to delete the election

Expected behavior
Deleting an election should always be possible to users with the permission to manage elections. State of election should not matter for this.

[reiterl]

The client sends 'assignment.delete' to the backend. The backend replied with that error message.
This seems to be more a backend problem to me.
The action description in the backend doesn't tell me about exception, changes, etc.

@Elblinator do you also see it this way and can you move this into the backend? Okay I found the button to transfer the issue.