Disable experimental server

Fixes #790

Author: lukaszsamson

apps/language_server/lib/language_server.ex

@@ -7,13 +7,17 @@ defmodule ElixirLS.LanguageServer do
   alias ElixirLS.LanguageServer
   alias ElixirLS.LanguageServer.Experimental
 
+  # @maybe_experimental_server [Experimental.Server]
+  @maybe_experimental_server []
+
   @impl Application
   def start(_type, _args) do
     children = [
       Experimental.SourceFile.Store,
       {ElixirLS.LanguageServer.Server, ElixirLS.LanguageServer.Server},
       Experimental.Server,
-      {ElixirLS.LanguageServer.PacketRouter, [LanguageServer.Server, Experimental.Server]},
+      {ElixirLS.LanguageServer.PacketRouter,
+       [LanguageServer.Server] ++ @maybe_experimental_server},
       {ElixirLS.LanguageServer.JsonRpc,
        name: ElixirLS.LanguageServer.JsonRpc, language_server: LanguageServer.PacketRouter},
       {ElixirLS.LanguageServer.Providers.WorkspaceSymbols, []},