Check if disposed as otherwise we can't fetch the data

If the dispose event arrives after the widget has be disposed (e.g. on
shutdown) then getData throws an exception.

This now checks first if the widget is already disposed and then simply
returns.

Author: laeubi

bundles/org.eclipse.e4.ui.workbench.renderers.swt/src/org/eclipse/e4/ui/workbench/renderers/swt/SWTPartRenderer.java

@@ -141,8 +141,11 @@ public void bindWidget(MUIElement me, Object widget) {
 			// Ensure that disposed widgets are unbound form the model
 			Widget swtWidget = (Widget) widget;
 			swtWidget.addDisposeListener(e -> {
-				MUIElement element = (MUIElement) e.widget
-						.getData(OWNING_ME);
+				Widget w = e.widget;
+				if (w.isDisposed()) {
+					return;
+				}
+				MUIElement element = (MUIElement) w.getData(OWNING_ME);
 				if (element != null)
 					unbindWidget(element);
 			});