Actually I have a number of errors. Not sure if some of it is because I am running the development version on an Arch derivative. I couldn't see the problem I had with Libreoffice mentioned anywhere either.
I'm not at my computer at present and also realise that some of this should be in an issue.
The 'story' :-
Created a dev environment as documented above.
Ran it and it detected my current install (2.4.?). It offered to backup and convert, so I let it do so.
Got crashes when editing songs. (hopefully if I restore from that backup, I can reproduce those).
Removed (or renamed?) the openlp data directory.
Run (with -l debug) and added songs etc.
When I run a presentation, with Libreoffice, it runs the first time but thereafter just flashes up and closes. Errors on the command line indicate that it can't be closed because it is in another thread.
Images are not displayed on the projection screen but do appear in the preview. Message on the command line indicate (known?) invalid ICC profile!? Tried changing the profile in GIMP but same error.