Fix a bad proc param test

[ike709]

Another Broken Test test that didn't actually work in BYOND. Also changed the obj to a datum for no particular reason.

Original:

This PR:

[amylizzle]

huh I swear byond used to do some fuckery if you passed null as an arg name

[ike709]

Not in this context. That involves shenanigans with proc overrides, like I told you on discord the other day.

[wixoaGit]

Not in this context. That involves shenanigans with proc overrides, like I told you on discord the other day.

I'm fairly sure using null as the name of an argument in any context would have that become the new null. This was probably fixed in newer versions of BYOND.