Prevent TypeError and incorrect state updates for "pageLoadStates"

Page load state updates of an already closed chapter caused TypeErrors or incorrect state updates.

src/modules/reader/utils/ReaderPager.utils.tsx

@@ -524,3 +524,8 @@ export const getScrollToXForReadingDirection = (
 
     return getOptionForDirection(-element.scrollWidth, 0, themeDirectionForReadingDirection);
 };
+
+export const isPageOfOutdatedPageLoadStates = (
+    url: string,
+    pageLoadState: ReaderStatePages['pageLoadStates'][number] | undefined,
+): boolean => pageLoadState === undefined || pageLoadState.url !== url;