Passing `undefined` as `ProxyHeader` argument to `cowboy_http:init/6` causes dialyzer error

[eseres]

Passing undefined in as the ProxyHeader argument causes a Dialyzer error because cowboy_http:init/6 specs it as ranch_proxy_header:proxy_info():

-spec init(pid(), ranch:ref(), inet:socket(), module(), ranch_proxy_header:proxy_info(), cowboy:opts()) -> ok.

However, request/5 function anticipates that ProxyHeader might actually be undefined which makes sense:

	Req = case ProxyHeader of
		undefined -> Req0;
		_ -> Req0#{proxy_header => ProxyHeader}
	end,

Could the spec for cowboy_http:init/6 be updated to accept undefined for the ProxyHeader argument?

[essen]

Thanks. How do you use it that you get a Dialyzer error? Do you call it directly?

undefined is indeed missing, I'm just curious as Dialyzer runs on the project don't catch it.

Feel free to send a PR by the way.

[eseres]

Yes, we call cowboy_http:init/6 directly. We do this because we use ranch to accept connections, then determine the protocol (HTTP vs. non-HTTP) and then if it is HTTP, we launch into Cowboy by calling cowboy_http:init/6. And we pass in undefined for the ProxyHeader.

I will create a PR.