Fix error calling 'current()' on an unknown route

[bakerkretzmar]

After this PR, instead of causing an error, calling route().current() on an unknown route (e.g. a route without a name) now returns undefined, and passing an invalid route name, for example route().current('this-route-name-doesnt-exist'), returns false.

Fixes #360.

[d13r]

Thanks for the quick fix. 👍

[dbcreator-studios]

route().current() still return undefined in latest version

[bakerkretzmar]

@dbcreator-studios if you call route().current() on an unnamed or unknown route, returning undefined is the expected behaviour.