Thanks for your answer! I’ve already solved it by allocating USplineComponent. If remember it correctly I did it in a different way, but your example looks much more cleaner.
Though the main question is if this behaviour of the editor should be treated as normal or as a bug, as being not able to open the project via the editor may be quite severe i.e. you don’t know what went wrong (i’m not sure if this is debuggable, maybe I’ve set something wrong…). Or should I treat the editor as a part of my project, and using VC as a base? (i.e. is it preferable to compile and start the editor from VC, as I’ve seen you can compile and then start an instance of the editor from VC).