guimanager | creating guis with chattriggers modules | Build Tool library

I am writing a program that displays patient records when entering a practitioner number (FHIR HAPI), but that is besides the point. I want to display basic patient details, and then through a checkbox, allow the user to add an extra column to the JTable that displays their details. This extra column should be able to be added and removed depending on the state of the checkbox. However, when I try to use my DefaultTableModel variable to perform the model.addColumn() method, I always get a NullPointer exception. The very last method is the one creating issues. I also provided code to the other methods that are called. I have tried using various types of arrays (Object and String) for the values and even arraylists. You will also see that in my second piece of code for the method getAllPatientObservationValues() I performed a println to see if it goes into the method and it does not. Any help will be much appreciated.

I'm trying to load a controller in the constructor, and to do so I have to call loader.load() first, otherwise getController() returns null, as I've read in multiple stackoverflow answers.