successful response shouldn't return error object

[prabirshrestha]

{
  "response": {
    "id": 1,
    "jsonrpc": "2.0",
    "result": {
      "capabilities": {
        "documentFormattingProvider": true,
        "renameProvider": true,
        "definitionProvider": true,
        "textDocumentSync": {
          "change": 1,
          "openClose": true
        },
        "completionProvider": {
          "resolveProvider": true
        }
      }
    },
    "error": null
  }
}

More info about this at prabirshrestha/vim-lsp#640 (comment)

// cc @dasJ who filed the issue on vim-lsp

[jD91mZM2]

Turns out I have this fixed by #2, I just forgot all about that PR :P

[jD91mZM2]

I think this is fixed now, since that PR got merged :)