While verifying {T116095} found this edge case:
1) Log in as a non-privileged user and go to any Flow board page.
2) Log in as Admin and go to the same Flow page that a non-privileged user is currently viewing.
3) Admin deletes a topic - a non-privileged user attempts to edit or to post a reply to a deleted topic. A user receives quite few error messages (some of them malformed) and none of them is helpful.
{F2977520}
```
Exception Caught: Conversion from 'topic-title-wikitext' to 'html' was requested, but this is not supported.
Edit a previous post: An error occurred.<br />The error message received was: internal_api_error_Flow\Exception\WikitextException
```
The UI displays weird messages - 'changes' become 'exchanges'
{F2977499}
a dimmed, transculent menu
{F2977528}
4) If a Flow board was deleted while another user session is still active - a warning ( little bit cryptic) is displayed:
```
Page provided does not have Flow enabled and allowCreation failed with: User does not have the "Create Flow boards in any location" permission
```
Console shows: Uncaught TypeError: Cannot read property 'view-post' of undefined