Fix #4944: Game crashes upon selecting objects in scenario editor

When the filter caused no results to be shown in the list, it would try to realloc for 0 bytes which returns NULL. The error shown in the console was a minor bug, the more serious issue was the the original memory was freed but the list pointer not updated. Instead just check for 0 items, dispose the list and return.

src/openrct2/windows/editor_object_selection.c

@@ -390,6 +390,13 @@ static void visible_list_refresh(rct_window *w)
 		}
 	}
 
+	if (_numListItems == 0)
+	{
+		visible_list_dispose();
+		window_invalidate(w);
+		return;
+	}
+
 	void *new_memory = realloc(_listItems, _numListItems * sizeof(list_item));
 	if (new_memory == NULL) {
 		log_error("Unable to reallocate list items");