Error when I type the password correctly.

[Rongyu68]

~/keystroke-dynamics-datagen$ python3 record_keystroke.py
Enter your name: alex_rep1
enter 2 times more!
Enter '.tie5Roanl' : .tie5Roanl
pwd correct!
Traceback (most recent call last):
File "record_keystroke.py", line 99, in
key_timings[key.lower()]["keyDown"] - key_timings[key]["keyUp"]
TypeError: unsupported operand type(s) for -: 'float' and 'NoneType'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "record_keystroke.py", line 102, in
key_timings[key]["keyDown"] - key_timings[key]["keyUp"]
TypeError: unsupported operand type(s) for -: 'NoneType' and 'NoneType'

Could you please tell me how to debug with that?