fix: fix exception when posting forms

Author: realth000

lib/features/authentication/repository/models/user_credential.dart

@@ -86,7 +86,7 @@ class UserCredential with UserCredentialMappable {
   final SecurityQuestion? securityQuestion;
 
   /// Method to convert to json.
-  Map<String, dynamic> toJson() {
+  Map<String, String> toJson() {
     final m = {
       'fastloginfield': loginField.toString(),
       'username': loginFieldValue,

lib/features/checkin/utils/do_checkin.dart

@@ -45,7 +45,13 @@ Task<CheckinResult> doCheckin(NetClientProvider netClient, CheckinFeeling feelin
       return const CheckinResultFormHashNotFound();
     }
 
-    final body = {'formhash': formHash, 'qdxq': feeling.toString(), 'qdmode': 1, 'todaysay': message, 'fastreply': 1};
+    final body = <String, String>{
+      'formhash': formHash,
+      'qdxq': feeling.toString(),
+      'qdmode': '1',
+      'todaysay': message,
+      'fastreply': '1',
+    };
 
     final checkInRespEither = await netClient.postForm(_checkInRequestUrl, data: body).run();
     if (checkInRespEither.isLeft()) {