only show error dialog when visualized

tools/cooja/java/se/sics/cooja/GUI.java

@@ -420,9 +420,9 @@ public class GUI extends Observable {
       			"To manage COOJA projects:\n" +
       			"Menu->Settings->COOJA projects",
       			"Reconfigure COOJA projects", JOptionPane.INFORMATION_MESSAGE);
-      }
       	showErrorDialog(getTopParentContainer(), "COOJA projects load error", e, false);
       }
+    }
 
     // Start all standard GUI plugins
     for (Class<? extends Plugin> pluginClass : pluginClasses) {