Requests with no result now yields a response with empty result

[mrbech]

So similarly to #39 I also ran into that https://github.com/natebosch/vim-lsc sends a "shutdown" request, waits for a response (with timeout of 5 seconds) and then sends an "exit" to the language server. With this language server, it times out (so vim takes 5 seconds to close).

This is because the fsharp language server does not respond to requests where there is no result (like "shutdown"), the specification (https://microsoft.github.io/language-server-protocol/specification) defines:

Every processed request must send a response back to the sender of the request.

So I made the change here and tested with vim-lsc and it works :)
As I see it this shouldn't create any issues with other clients.

[georgewfraser]

Thanks!

[georgewfraser]

@mrbech would you mind checking this all still works after ec7f63f

[mrbech]

Still works, thanks 👍