Pasting a clip sometimes fails without a clear reason
Pasting right now works wonky at best - if it succeeds, you can easily paste one clip multiple times, but quite often it decides to fail and prevents pasting said clip completely until it's copied again. It is not clear to the end user when and why that happens - making for a poor UX.
It fails pretty consistently if the newly pasted clip would go through an already existing crossfade (understandable - but should be communicated to the user), but sometimes it just fails without a clear reason.
Such failure is usually not even noted in the normal console output, but if we try to CTRL+V again, an error from the underlying GES C library is shown:
indicating that we should at least be emptying self.__copied_group
around this line after a pasting failure occurs.
Pitivi 2021.01.1
GES 1.19.0.1
GTK+ 3.24
GStreamer 1.19.0.1