Standardise frontend hook fetch error handling and mark Task 12 done

frontend/src/hooks/useMapData.ts

@@ -4,6 +4,7 @@
 
 import { useCallback, useEffect, useRef, useState } from "react";
 import { fetchBansByCountry } from "../api/map";
+import { handleFetchError } from "../utils/fetchError";
 import type { BansByCountryResponse, MapBanItem, TimeRange } from "../types/map";
 import type { BanOriginFilter } from "../types/ban";
 
@@ -68,9 +69,7 @@ export function useMapData(
           setData(resp);
         })
         .catch((err: unknown) => {
-          if (err instanceof Error && err.name !== "AbortError") {
-            setError(err.message);
-          }
+          handleFetchError(err, setError, "Failed to fetch map data");
         })
         .finally((): void => {
           setLoading(false);