Error message "FATAL: Input parameter is required."

When I run the tool with "oad compare oldspec newspec" I get the error: "FATAL: Input parameter is required." I turned up logging to but was not able to get any helpful information. Any ideas?

Start by reproducing the `oad compare oldspec newspec` command and inspect the command entry point and argument handling. Trace why the two supplied specification arguments produce “FATAL: Input parameter is required.” Done means the command accepts both inputs and reports the comparison result or a more actionable validation error.

Written by the indexing model from the issue text.