Fix incorrect check in issuer_or_subject_length function

[akgamerz790]

This PR fixes the logic error in the issuer_or_subject_length function described in issue #30.

Problem:
The else clause was incorrectly attached to the if common: statement, meaning the TypeError would only be raised if the common parameter was falsy, rather than checking if any certificate information was provided.

Solution:
Changed the logic to check if not tot_len: after all parameters have been processed, ensuring the TypeError is raised when no certificate information is provided, regardless of which parameter is missing.

Changes:

• Fixed incorrect else clause placement in issuer_or_subject_length function
• The function now properly validates that at least one certificate parameter has a value

Fixes #30

[dhalbert]

Thanks for the fix. I made it more general so it also checks for accidental negative lengths. I also changed it to a ValueError, because the problem is with the value, not the type.