src/java.desktop/macosx/classes/sun/lwawt/macosx/CPlatformWindow.java

@@ -676,11 +676,11 @@
     @Override  // PlatformWindow
     public void toFront() {
         final long nsWindowPtr = getNSWindowPtr();
         LWCToolkit lwcToolkit = (LWCToolkit) Toolkit.getDefaultToolkit();
         Window w = DefaultKeyboardFocusManager.getCurrentKeyboardFocusManager().getActiveWindow();
-        if( w != null
+        if( w != null && w.getPeer() != null
                 && ((LWWindowPeer)w.getPeer()).getPeerType() == LWWindowPeer.PeerType.EMBEDDED_FRAME
                 && !lwcToolkit.isApplicationActive()) {
             lwcToolkit.activateApplicationIgnoringOtherApps();
         }
         updateFocusabilityForAutoRequestFocus(false);