Deck calendars cannot be deleted

How to use GitHub

• Please use the 👍 reaction to show that you are affected by the same issue.
• Please don't comment if you have no relevant information to add. It's just extra noise for everyone subscribed to this issue.
• Subscribe to receive notifications on status change and new comments.

Describe the bug
Calendars which were created while creating a new deck cannot be deleted. The following message is shown: "An error occurred, unable to delete the calendar."

To Reproduce
Steps to reproduce the behavior:

1. Create a new board in Deck
2. Change to the Calendar
3. Delete the calendar for the created board via "..." -> "Delete"
4. Wait X seconds (7 in my case) for the system to detele the calendar
5. This message is shown "An error occurred, unable to delete the calendar." and the calendar still exists

Expected behavior
The calendar should be deleted

System details
Nextcloud 20.0.7
Calendar 2.1.3
Deck 1.2.4

I´m happy to provide more information if needed.

Thanks a lot!

Start by reproducing the deletion failure using the reported Nextcloud 20.0.7, Calendar 2.1.3, and Deck 1.2.4 versions, then trace the Deck calendar deletion action from the UI through its request and error response. Done means a calendar created with a new board can be deleted and no longer appears.