WI #1622 Add unhandled exception handler. (#1812)

* WI #1622 Add unhandled exception handler.

* WI #1622 Enforce with AppDomain and add destructor

Co-authored-by: mayanje <jeanchrysostome.mayan@e-i.com>

Author: mayanje

TypeCobol.LanguageServer/JsonRPC/IRPCServer.cs

@@ -29,5 +29,10 @@ public interface IRPCServer
         /// Write a trace in the server log file
         /// </summary>
         void WriteServerLog(string trace);
+
+        /// <summary>
+        /// An Unhandled Exception handler
+        /// </summary>
+        UnhandledExceptionEventHandler Handler { get; set; }
     }
 }

TypeCobol.LanguageServer/JsonRPC/JsonRPCServer.cs

@@ -81,6 +81,11 @@ private void PrepareJsonPRCMessage(JObject jsonMessage)
         // Remeber all requests sent and still waiting for a response 
         private IDictionary<string, ResponseWaitState> responsesExpected = new Dictionary<string, ResponseWaitState>();
 
+        /// <summary>
+        /// An Unhandled Exception handler
+        /// </summary>
+        public UnhandledExceptionEventHandler Handler { get; set; }
+
         /// <summary>
         /// Send an async request to the client and await later for the response or error
         /// </summary>
@@ -166,6 +171,7 @@ private void HandleNotification(string method, JToken parameters)
                 }
                 catch(Exception e)
                 {
+                    Handler?.Invoke(this, new UnhandledExceptionEventArgs(e, false));
                     WriteServerLog(String.Format("Notification handler for {0} failed : {1}", notificationType.GetType().Name, e.Message));
                     ResponseResultOrError error = new ResponseResultOrError() { code = ErrorCodes.InternalError, message = e.Message , data = parameters?.ToString() };
                     Reply(method, error);
@@ -196,6 +202,7 @@ private void HandleRequest(string method, string requestId, JToken parameters)
                 }
                 catch(Exception e)
                 {
+                    Handler?.Invoke(this, new UnhandledExceptionEventArgs(e, false));
                     ResponseResultOrError error = new ResponseResultOrError() { code = ErrorCodes.InternalError, message = e.Message };
                     Reply(requestId, error);
                 }
@@ -259,6 +266,7 @@ private void HandleResponse(string requestId, JToken result, JToken error)
                 }
                 catch (Exception e)
                 {
+                    Handler?.Invoke(this, new UnhandledExceptionEventArgs(e, false));
                     WriteServerLog(String.Format("Task completion for the response expected by request {0} of type {1} failed : {2}", requestId, requestType.GetType().Name, e.Message));
                 }
             }

TypeCobol.LanguageServer/VsCodeProtocol/LanguageServer.cs

@@ -41,15 +41,42 @@ public LanguageServer(IRPCServer rpcServer)
 
             RemoteConsole = new RemoteConsole(rpcServer);
             RemoteWindow = new RemoteWindow(rpcServer);
+
+            //Track any unhandled exception during rpc communication from the server
+            rpcServer.Handler += UnhandledExceptionHandler;
+            //Also enforce with AppDomain unhandled exception handler
+            AppDomain currentDomain = AppDomain.CurrentDomain;
+            currentDomain.UnhandledException += UnhandledExceptionHandler;
+        }
+
+        /// <summary>
+        /// Destructor.
+        /// </summary>
+        ~LanguageServer()
+        {
+            this.RpcServer.Handler -= UnhandledExceptionHandler;
+            AppDomain currentDomain = AppDomain.CurrentDomain;
+            currentDomain.UnhandledException -= UnhandledExceptionHandler;
         }
 
         // RPC server used to send Remote Procedure Calls to the client
         protected IRPCServer RpcServer { get; }
 
-        public void NotifyException(Exception e)
+        /// <summary>
+        /// Unhandled Exception Event Handler
+        /// </summary>
+        /// <param name="sender">Sender of the unhandled exception</param>
+        /// <param name="e">Tne Exception event argument</param>
+        private void UnhandledExceptionHandler(object sender, UnhandledExceptionEventArgs e)
+        {
+            NotifyException(e.ExceptionObject as Exception);
+        }
+
+        public virtual void NotifyException(Exception e)
         {
-            AnalyticsWrapper.Telemetry.TrackException(e, null);
             this.RemoteWindow.ShowErrorMessage(e.Message + "\n" + e.StackTrace);
+            AnalyticsWrapper.Telemetry.TrackException(e, null);            
+            AnalyticsWrapper.Telemetry.SendMail(e, null, null, null);
         }
 
         public void NotifyWarning(string message)