refactored HTTP error handling and streamlined UI components by centralizing shared logic and removing redundant parameters

lib/api/marianumcloud/talk/chat/long_poll_chat.dart

@@ -1,10 +1,7 @@
-import 'dart:async';
-import 'dart:io';
-
 import 'package:http/http.dart' as http;
 
-import '../../../errors/network_exception.dart';
 import '../../../errors/server_exception.dart';
+import '../../../http_errors.dart';
 import '../../nextcloud_ocs.dart';
 import 'get_chat_params.dart';
 import 'get_chat_response.dart';
@@ -40,18 +37,12 @@ class LongPollChat {
     );
     final headers = NextcloudOcs.headers();
 
-    final http.Response response;
-    try {
-      response = await http
+    final response = (await sendGuarded(
+      'LongPollChat $uri',
+      () => http
           .get(uri, headers: headers)
-          .timeout(Duration(seconds: timeoutSeconds + 15));
-    } on TimeoutException catch (e) {
-      throw NetworkException.timeout(technicalDetails: 'LongPollChat $uri: $e');
-    } on SocketException catch (e) {
-      throw NetworkException(technicalDetails: 'LongPollChat $uri: ${e.message}');
-    } on http.ClientException catch (e) {
-      throw NetworkException(technicalDetails: 'LongPollChat $uri: ${e.message}');
-    }
+          .timeout(Duration(seconds: timeoutSeconds + 15)),
+    ))!;
 
     final status = response.statusCode;
     if (status == 304) return null;