It has been a couple days I was loosing my last hair and brain cells over an unexplained nil object exception in my last project. I finally cornered the gremlin, in the most unusual of places : in a computed property, I set TextArea1.StyledText.RTFData. It appears I was doing that too early in the program.
Now I have put that into an if not nil block. Crash gone 
Sigh of relief …