Merge pull request #9320 from MBR-0001/master

Fix NRE in DisposeAsyncCore

Emby.Server.Implementations/ApplicationHost.cs

@@ -1184,6 +1184,8 @@ namespace Emby.Server.Implementations
                 }
             }
 
+            if (_sessionManager != null)
+            {
                 // used for closing websockets
                 foreach (var session in _sessionManager.Sessions)
                 {
@@ -1191,4 +1193,5 @@ namespace Emby.Server.Implementations
                 }
             }
         }
+    }
 }