Add check to prevent md5 from running with no author name

[chrisjtang]

Description

These changes add an additional check to prevent the md5() function from running with a null first parameter.

Motivation and Context

#140 (comment)

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
  • I have updated the documentation accordingly.
• All new and existing tests passed.