List index out of range error, how to fix?

Question

Python

I can't figure out what's wrong. either the list overflows or the index does not exist. but everything is printed, so most likely the first. I hope someone understands. I won't upload all the code. If you need additions, I will be happy to provide.

test_test = dict()

        for i in range(len(self.resultDict['materials'])):
            print(self.resultDict['materials'][i]['material_id'], i)
            if self.resultDict['materials'][i]['material_id'] not in test_test:
                test_test[self.resultDict['materials'][i]['material_id']] = list()
            test_test[self.resultDict['materials'][i]['material_id']].append(i)

            if self.resultDict['materials'][i]['color_id'] not in test_test:
                print(self.resultDict['materials'][i]['color_id'], i)
                test_test[self.resultDict['materials'][i]['color_id']] = list()
            test_test[self.resultDict['materials'][i]['color_id']].append(i)
      
            if self.resultDict['materials'][i]['depth_id'] not in test_test:
                test_test[self.resultDict['materials'][i]['depth_id']] = list()
            test_test[self.resultDict['materials'][i]['depth_id']].append(i)

if you remove the last two if-a, then everything is done. crashes before converting to pdf.