Closing a review with a deleted unresolved comment results in 'Problem with transitioning the review' message

Issue Summary

A warning about unresolved comments pops up when closing a review that had deleted unresolved comments.

Steps to Reproduce

1. Create a new code review (e.g. from a patch).
2. Create a review comment.
3. Mark the new comment as 'Needs resolution'.
4. Delete the new comment.
5. Close the review.
6. A pop up "Problem with transitioning the review" is displayed
7. Click 'Proceed'.
8. The review is closed.

Expected Results

If there are no comments, the review should close without warning about unresolved comments.

Actual Results

A pop up "Problem with transitioning the review" is displayed

Notes

The warning does not prevent the review from closing, so the "problem with transitioning" is misleading.
Furthermore, this produces no errors or warnings in the logs (with DEBUG on).

Workaround

Currently there is no known workaround for this behavior. A workaround will be added here when available