if sub-protocol is nil, don't use it in constructor

[jmarca]

Minor edit. conditional to check if the sub-protocol is nil, then don't use it when constructing the websocket. Otherwise, sub-protocol is still sent as nil, whereas the expected behavior is to not send any sub-protocols

[jmarca]

Note that I didn't touch the clj branch, because I didn't want to break anything there, but it might need the same conditional.

And also, apologies but no test...I currently have zero skills at testing cljs.

[jmarca]

I think this also relates to #53

[oliyh]

Thank you, good catch. I'll tweak the clj implementation. There are no tests for this bit of code yet as it would require an integration test environment which is currently blocked by #63

[jmarca]

I didn’t catch it, it caught me! And it is simple enough even my basic clojurescript skills can fix it.

James