Update alchemist-swingui/src/main/java/it/unibo/alchemist/boundary/swingui/monitor/impl/Generic2DDisplay.java

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: DanySK

alchemist-swingui/src/main/java/it/unibo/alchemist/boundary/swingui/monitor/impl/Generic2DDisplay.java

@@ -370,7 +370,12 @@ private void updateHookedNodeView() {
         if (hooked.isEmpty()) {
             return;
         }
-        final P hookedCoordinates = positions.get(hooked.get());
+        final Node<T> hookedNode = hooked.get();
+        final P hookedCoordinates = positions.get(hookedNode);
+        if (hookedCoordinates == null) {
+            hooked.set(Optional.empty());
+            return;
+        }
         final Point hookedPoint = wormhole.getViewPoint(hookedCoordinates);
         if (hookedPoint.distance(getCenter()) > FREEDOM_RADIUS) {
             wormhole.setViewPosition(hookedPoint);