Add new tab button in File Manager launched Delete Virtual Server command

I had just deleted a virtual subdomain, then switched to Webmin -> Others -> File Manager. I was about to do some file work and decided I wanted two file explorer tabs at the same time. I clicked the big + button for adding a tab and the main content part of the browser page became a warning page about deleting a virtual server. I just clicked refresh on Firefox and things work normal again.

I did have one file open for editing at that time but hadn't made edits yet.