I made some tiny progres. I have been able to open my project by first removing the last map asset I was working on from the content folder (assuming that either the map has become corrupted or an asset that is referenced in it).
Notabaly, this does not save the project from crashing. Immediately after startup the editor starts “discovering asset data”. After a while when it gets to an asset I suppose, it crashes again. Unfortunately the log does not seem to show any consistent results that would help to pinpoint the culprit…
Also, I noticed that when I open a specific folder in which my skeletal meshes are, the editor almost immediately crashes.
I guess I will have to start deleting the assets one by one…