allow users to inject their own jsonRpc customizations

Author: baronfel

src/LanguageServerProtocol.fs

@@ -12,6 +12,7 @@ module Server =
   open Newtonsoft.Json
   open Ionide.LanguageServerProtocol.JsonUtils
   open Newtonsoft.Json.Linq
+  open StreamJsonRpc
 
   let logger = LogProvider.getLoggerByName "LSP Server"
 
@@ -77,23 +78,28 @@ module Server =
     | ErrorExitWithoutShutdown = 1
     | ErrorStreamClosed = 2
 
+
+  /// The default RPC logic shipped with this library. All this does is mark LocalRpcExceptions as non-fatal
+  let defaultRpc (handler: IJsonRpcMessageHandler) =
+    { new JsonRpc(handler) with
+        member this.IsFatalException(ex: Exception) =
+          match ex with
+          | :? LocalRpcException -> false
+          | _ -> true }
+
   let startWithSetup<'client when 'client :> Ionide.LanguageServerProtocol.ILspClient>
     (setupRequestHandlings: 'client -> Map<string, Delegate>)
     (input: Stream)
     (output: Stream)
     (clientCreator: (ClientNotificationSender * ClientRequestSender) -> 'client)
+    (customizeRpc: IJsonRpcMessageHandler -> JsonRpc)
     =
 
     use jsonRpcHandler = new HeaderDelimitedMessageHandler(output, input, jsonRpcFormatter)
     // Without overriding isFatalException, JsonRpc serializes exceptions and sends them to the client.
     // This is particularly bad for notifications such as textDocument/didChange which don't require a response,
     // and thus any exception that happens during e.g. text sync gets swallowed.
-    use jsonRpc =
-      { new JsonRpc(jsonRpcHandler) with
-          member this.IsFatalException(ex: Exception) =
-            match ex with
-            | :? LocalRpcException -> false
-            | _ -> true }
+    use jsonRpc = customizeRpc jsonRpcHandler
 
     /// When the server wants to send a notification to the client
     let sendServerNotification (rpcMethod: string) (notificationObj: obj) : AsyncLspResult<unit> =