From David Gerard on the en.wp feedback page: if you go to add a reference and then choose not to continue and exit out of the template and save the page instead of going back, VisualEditor creates an empty closed reference tab </re>. See here:
https://en.wikipedia.org/w/index.php?title=User:David_Gerard&diff=562600190&oldid=545746964
Version: unspecified
Severity: minor
See Also:
https://bugzilla.wikimedia.org/show_bug.cgi?id=52182