Add an empty string check because is_num("") == T.

[keithjjones]

🗣 Description

is_num("") evaluates to True, but for our cases it needs to be false because we do a to_count() later.

💭 Motivation and context

Because it was a bug in some pcaps I tested.

🧪 Testing

There were no tests for me to hook into.

✅ Pre-approval checklist

• [X] This PR has an informative and human-readable title.
• [X] Changes are limited to a single goal - eschew scope creep!

✅ Pre-merge checklist

• [ ] Revert dependencies to default branches.
• [ ] Finalize version.

✅ Post-merge checklist

• [ ] Add a tag or create a release.

[mmguero]

Great, would you please add that same check to the other location in that file where is_num is used?

[keithjjones]

Great, would you please add that same check to the other location in that file where is_num is used?

Absolutely! Committed.