simplified code across the app and consolidated duplicated helpers

lib/api/marianumconnect/queries/get_ticker_page/get_ticker_page.dart

@@ -2,8 +2,8 @@ import 'dart:convert';
 
 import 'package:dio/dio.dart';
 
+import '../../../errors/app_exception.dart';
 import '../../../errors/ticker_content_unavailable_exception.dart';
-import '../../errors/marianumconnect_error.dart';
 import '../../marianumconnect_query.dart';
 import 'get_ticker_page_response.dart';
 
@@ -14,26 +14,20 @@ import 'get_ticker_page_response.dart';
 /// 404 `{ "error": "CONTENT_UNAVAILABLE", "webUrl": ... }`; that case is mapped
 /// to a dedicated [TickerContentUnavailableException] carrying the browser
 /// fallback URL, so the detail screen can offer "open in browser" instead of a
-/// generic error. The bespoke 404 handling is why this keeps its own try/catch
-/// instead of the base [guard].
+/// generic error.
 class GetTickerPage extends MarianumConnectQuery {
   final String slug;
 
   GetTickerPage(this.slug, {super.dio});
 
-  Future<TickerPageResponse> run() async {
-    try {
-      final response = await dio.get<Map<String, dynamic>>(
-        endpoint('ticker/pages/${Uri.encodeComponent(slug)}'),
-      );
-      return TickerPageResponse.fromJson(response.data!);
-    } on DioException catch (e) {
-      throw _mapError(e);
-    }
-  }
+  Future<TickerPageResponse> run() => getObject(
+    'ticker/pages/${Uri.encodeComponent(slug)}',
+    TickerPageResponse.fromJson,
+  );
 
-  Object _mapError(DioException e) {
-    final response = e.response;
+  @override
+  AppException mapError(DioException error) {
+    final response = error.response;
     if (response?.statusCode == 404) {
       final body = _asMap(response?.data);
       if (body != null && body['error'] == 'CONTENT_UNAVAILABLE') {
@@ -44,7 +38,7 @@ class GetTickerPage extends MarianumConnectQuery {
         );
       }
     }
-    return mapMarianumConnectError(e);
+    return super.mapError(error);
   }
 
   Map<String, dynamic>? _asMap(dynamic data) {