Uninstallable extension updates

In Extension manager there are two available extension updates that are shown when I check “Show all updates”.

In one of them (alternative searching), if I select it I get:

An error occurred:
EndTag: '</' not found
Line: 67
Column: 8

There’s no real update of this extension. This must be some error encountered in some past operation.
And the other (Zotero LO integration) shows:

An error occurred:
Document is empty
Line: 1
Column: 1

Again, this is most probably some failed installation in the past.
How do I get rid of these error messages?

… and you are using which version of LibreOffice on which operating system (you are really not a newbie on this site and should be familiar with the importance of this information for the sake of getting a sound answer)?