Fix type definition for route() with only options

[bram-pkg]

The order of function definitions was disallowing route(undefined, undefined, undefined, config) to be matched. This PR fixes that.

I've also added a test to ensure this doesn't fail again in the future.

[bakerkretzmar]

Thanks! I could have sworn I put them in the previous order specifically to avoid an issue like this where one of the definitions wasn't getting matched, but clearly your fix here works.

[bram-pkg]

Thanks!