Merge pull request 'Fix ChangeManagerWrapper' (#8) from b/javafx-wrapper-properties into develop

Reviewed-on: https://git.kske.dev/zdm/undo-redo/pulls/8
Reviewed-by: DieGurke <maxi@kske.dev>
Reviewed-by: delvh <leon@kske.dev>

javafx/src/main/java/dev/kske/undoredo/javafx/ChangeManagerWrapper.java

@@ -47,6 +47,7 @@ public class ChangeManagerWrapper<C extends Change, M extends ChangeManager<C>>
 	 */
 	public ChangeManagerWrapper(M manager) {
 		this.manager = manager;
+		updateProperties();
 	}
 
 	@Override

javafx/src/main/java/dev/kske/undoredo/javafx/ObservableChangeManager.java

@@ -21,7 +21,7 @@ public interface ObservableChangeManager<C extends Change> extends ChangeManager
 
 	@Override
 	default Optional<C> getLastChange() {
-		return Optional.of(lastChangeProperty().get());
+		return Optional.ofNullable(lastChangeProperty().get());
 	}
 
 	ReadOnlyBooleanProperty atMarkedChangeProperty();