A nullpointer should never happen and thus won't give you a clue as to why it's occurring, there is no error information.
Analyzing the unobfuscated stacktrace though, this seems to be happening due to some enumeration not having an image. You probably set the property 'Enumeration format' of a dynamic label to 'Image' while the enumeration used does not have an image. I will file a ticket for it since I just built a reproduction case, but you can easily fix this yourself in your project.
Edit: Since it was a small fix, I fixed it already, it will be released in 4.5.0