In the code:
steam_client.login('username', 'password', r'path\to\file\steamguard.maFile') (Placeholders used)
The error is thrown:
Exception has occurred: JSONDecodeError
Expecting value: line 1 column 1 (char 0)
StopIteration: 0
During handling of the above exception, another exception occurred:
json.decoder.JSONDecodeError: Expecting value: line 1 column 1 (char 0)
The Steam Guard file doesn't appear to be the issue as steam-tradeoffer-manager likes the file just fine and encounters no issue.
Steam does recognize a login, but the library still throws the same error no matter what