The custom LAF is not absolutely stable. It is at the moment the main crashing reason on my side. To overcome this I generally develop without and activate it the later I can.
I’ve never found a way to point at the reason it crashes as all my attempts showed me it is always something else...
However @Christoph-Hart said a few weeks ago that one should definitely not use external variables in a custom LAF or sure it will cause some troubles.
About that I still have no answer if we can use external colour values or if this enters in the same paradigm, And what about using a loaded path...