Project privacy set to public. By default, its content is available to everyone (authenticated or not). Please note that more restrictive permissions might exist on some items.
If a user set a tracker report private and there is no more public report, all other users lose artifacts visibility. This is disturbing and may be stressing.
What do you think about adding an alert to warn the user that he is about to remove the last public report?
Or, otherwise, ensure to always keep a default and public report.