Application freezes when I type an uppercase M

[sheenagibbs]

I am having lots of weird issues with certain key strokes killing the app, but uppercase M is probably the most annoying one that I know for sure is an issue.

Here's the error:
Exception in thread Thread-8 (listen):
Traceback (most recent call last):
File "/usr/lib/python3.11/threading.py", line 1038, in _bootstrap_inner
self.run()
File "/usr/lib/python3.11/threading.py", line 975, in run
self._target(*self._args, **self._kwargs)
File "/usr/local/lib/python3.11/dist-packages/keyboard/init.py", line 294, in listen
_os_keyboard.listen(self.direct_callback)
File "/usr/local/lib/python3.11/dist-packages/keyboard/_nixkeyboard.py", line 141, in listen
callback(KeyboardEvent(event_type=event_type, scan_code=scan_code, name=name, time=time, device=device_id, is_keypad=is_keypad, modifiers=pressed_modifiers_tuple))
File "/usr/local/lib/python3.11/dist-packages/keyboard/init.py", line 236, in direct_callback
if not all(hook(event) for hook in self.blocking_hooks):
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/local/lib/python3.11/dist-packages/keyboard/init.py", line 236, in
if not all(hook(event) for hook in self.blocking_hooks):
^^^^^^^^^^^
File "/usr/local/lib/python3.11/dist-packages/keyboard/init.py", line 474, in
return hook(lambda e: e.event_type == KEY_UP or callback(e), suppress=suppress)
^^^^^^^^^^^
File "/home/zero/zerowriter1/e-Paper/RaspberryPi_JetsonNano/python/examples/zerowriter.py", line 743, in handle_key_press
self.input_content += char
TypeError: can only concatenate str (not "NoneType") to str