Instead of printing the stack trace it would be much more helpful to just read:

1. Location of the problem in the FXML file (Locator)
2. Information about the problem (e.g.: reflection problem into controller. xyz not found in controller or wrong type or ...)
3. Method 'xyz' in FXML file not found in controller 'abc'. 'xyz' used in scene object 'blabla' for action 'some' (well this would help in finding a method call in the scene builder at all)

This would speed up development quite much.