Issue content gets lost if user deletes an attachment
Given is an already existing issue with one or more attachments. A user wants to edit this issue and add a comment, so he clicks "Edit". While editing and adding the issue's text, he notices an unwanted attachment in the issue head (in the yellow box on top of an issue) - so he clicks the small trash bin icon right to the attachment. The user gets asked if he is sure to delete this file, so he clicks "Yes". Now all of his text changes are gone because Redmine reloads the issue page! And it doesn't even warn the user that all of his changes will get lost.
To resolve this issue, I suggest a solution similar to when a user wants to close a browser tab while there is still an unsaved issue edit. Here the user gets asked if he really wants to close this tab.
The Redmine version is 3.4.5, and I also confirmed this with an older Redmine 2.6.2.