Server.fs: don't crash the server when handler crashes

Previous commit on this apparently didn't do the job right.

Related:
- #44

Author: razzmatazz

CHANGELOG.md

@@ -3,6 +3,10 @@ All notable changes to this project will be documented in this file.
 
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
+## [Unreleased]
+
+* Fix an issue intermittent server crashing after upgrading to latest Ionide.LanguageServerProtocol;
+
 ## [0.5.4] - 2022-08-20 / Šilavotas
   https://www.lrytas.lt/kultura/istorija/2021/08/07/news/kitoks-kaimas-prienu-rajone-kurio-neisdraske-net-sovietu-valdzia-bendruomenes-nariais-tampa-ir-kaunieciai-20347142
 * Upgrade roslyn libs to 4.4.0-1.final;

src/CSharpLanguageServer/Server.fs

@@ -1008,15 +1008,17 @@ let setupServerHandlers options (lspClient: LspClient) =
 
             try
                 let scope = ServerRequestScope(state, stateActor.Post, logMessage)
-                try
-                    return! asyncFn scope param
-                with
-                | ex ->
-                    let unpackedEx = ex |> unpackException
-                    if (unpackedEx :? TaskCanceledException) || (unpackedEx :? OperationCanceledException) then
-                        return LspResult.requestCancelled
-                    else
-                        return LspResult.internalError (string ex)
+
+                let! resultOrExn = (asyncFn scope param) |> Async.Catch
+
+                return
+                    match resultOrExn with
+                    | Choice1Of2 result -> result
+                    | Choice2Of2 exn ->
+                        match exn with
+                        | :? TaskCanceledException -> LspResult.requestCancelled
+                        | :? OperationCanceledException -> LspResult.requestCancelled
+                        | _ -> LspResult.internalError (string exn)
             finally
                 stateActor.Post(FinishRequest requestId)
         }