Closing the app soon after deleting a task makes the task reappear

[Riksu9000]

Describe the bug
If I close the app soon after deleting a task, while the notification is still visible, the task will still be there after launching the app again.

To Reproduce
Steps to reproduce the behavior:

1. Delete a task
2. Close the app within a few seconds
3. Launch the app

Expected behavior
The task to be deleted.

Desktop (please complete the following information):

• Fedora, planify master

[alainm23]

The task has a waiting time before being completely deleted, if you close the application before then the functionality will not be able to execute.

[Riksu9000]

I get why it happens technically, but it's not consistent if I delete a task and the app says the task was deleted, but the task didn't really get deleted. I think the app should finish tasks like this before closing.