Fix possible nullrefs

Author: Arlodotexe

components/AppServices/src/AppServiceComponent.cs

@@ -462,7 +462,7 @@ private async void Connection_RequestReceived(AppServiceConnection sender, AppSe
                 try
                 {
                     // Try to get the registered endpoint with the command name, and invoke it
-                    if (_endpoints.TryGetValue(commandStr, out Func<AppServiceParameters, Task<object?>> endpoint))
+                    if (_endpoints.TryGetValue(commandStr, out Func<AppServiceParameters, Task<object?>>? endpoint) && endpoint is {})
                     {
                         response = await endpoint(new AppServiceParameters(this, sender, parameters));
                     }

components/AppServices/src/AppServiceHost.cs

@@ -204,9 +204,9 @@ private void AppServiceConnection_RequestReceived(AppServiceConnection sender, A
         if (args.Request.Message.TryGetValue(ProgressKey, out object? progressKey) &&
             args.Request.Message.TryGetValue(ProgressValue, out object? progressValue) &&
             progressKey is Guid id &&
-            _progressTrackers.TryGetValue(id, out IProgress<object> progress))
+            _progressTrackers.TryGetValue(id, out IProgress<object>? progress))
         {
-            progress.Report(progressValue);
+            progress?.Report(progressValue);
         }
     }