Null pointer check in legacy Choose command

Assets/Fungus/Narrative/Deprecated/Choose.cs

@@ -177,9 +177,12 @@ namespace Fungus
 					options.Clear();
 					showBasicGUI = false;
 					Stop();
+					if (option.targetBlock != null)
+					{
 						option.targetBlock.Execute();
 					}
 				}
+			}
 			
 			GUILayout.EndVertical();