fix: Request get options.headers null error

lib/http/init.dart

@@ -212,7 +212,8 @@ class Request {
     if (extra != null) {
       if (extra['ua'] != null) {
         options ??= Options();
-        options.headers!['user-agent'] = headerUa(type: extra['ua']);
+        options.headers ??= <String, dynamic>{};
+        options.headers?['user-agent'] = headerUa(type: extra['ua']);
       }
     }
     try {

lib/pages/member_archive/view.dart

@@ -117,7 +117,7 @@ class _MemberArchivePageState extends State<MemberArchivePage> {
                   }
                 } else {
                   return HttpError(
-                    errMsg: snapshot.data['msg'],
+                    errMsg: snapshot.data?['msg'] ?? '请求异常',
                     fn: () {},
                   );
                 }