Sorting with only one annotation

[mzur]

If there is only one annotation in Largo and I select it as a reference for sorting by similarity it is shown twice:

While sorting with only one annotation makes no sense, this should be handled gracefully. No request should be sent to the backend and with similarity sorting only the pinned annotation should be shown.

[mzur]

This is the code that is called when a new similarity sorting should be active. Maybe it is enough to fall through to the else case with an empty array when there is only a single annotation.