Not setting the clipping rectangle crashes application

In the attached program, in order not to draw outside of the bounds of the drawingPane
I set a clipping Rectangle. This works nicely although it is
a bit of a pain that we still have to do that manually.
But even worse if you don't do that the whole application
crashes at startup caused by a StackOverfowError. I'd rather
expect some drawing artifacts on the tool bar but not a crash
of the application.