port-part being null is not handled

[evilpie]

port-part is explicitly set to null, but port-part match doesn't handle it.

6.7.2.8. Does url match expression in origin with redirect count?

Step 3.4. Let port-part be expression’s port-part if present, and null otherwise.
Step 3.5. If port-part does not port-part match url, return "Does Not Match".

port-part match

Step 1. Assert: input is the empty string, "*", or a sequence of ASCII digits.