ignatandrei
diff --git a/‎src/NetCore2Blockly/NetCore2Blockly/GenerateBlocklyFilesHostedService.cs‎
Lines changed: 7 additions & 3 deletions b/‎src/NetCore2Blockly/NetCore2Blockly/GenerateBlocklyFilesHostedService.cs‎
Lines changed: 7 additions & 3 deletions
diff --git a/‎src/NetCore2Blockly/TestBlocklyHtml/wwwroot/butterfly-led.png‎
-5.37 KB b/‎src/NetCore2Blockly/TestBlocklyHtml/wwwroot/butterfly-led.png‎
-5.37 KB
diff --git a/‎src/NetCore2Blockly/TestBlocklyHtml/wwwroot/butterfly.png‎
-91.2 KB b/‎src/NetCore2Blockly/TestBlocklyHtml/wwwroot/butterfly.png‎
-91.2 KB
@@ -691,10 +691,14 @@ internal void registerCallback()
             cp.GetChangeToken().RegisterChangeCallback(a =>
             {
 
-
                 var s = a as GenerateBlocklyFilesHostedService;
-                s.DoWork(null);
-                s.registerCallback();
+                if (s == null)
+                    return;
+                lock (s)
+                {
+                    s.DoWork(null);
+                    s.registerCallback();
+                }
             }, this);
 
         }