Образован хелпер Error, в который вынесены все коды ошибок.

Подкорректирован errorDict на фронте

common/helpers/Error.php

@@ -0,0 +1,63 @@
+<?php
+namespace common\helpers;
+
+final class Error {
+
+    const USERNAME_REQUIRED = 'error.username_required';
+    const USERNAME_TOO_SHORT = 'error.username_too_short';
+    const USERNAME_TOO_LONG = 'error.username_too_long';
+    const USERNAME_INVALID = 'error.username_invalid';
+    const USERNAME_NOT_AVAILABLE = 'error.username_not_available';
+
+    const EMAIL_REQUIRED = 'error.email_required';
+    const EMAIL_TOO_LONG = 'error.email_too_long';
+    const EMAIL_INVALID = 'error.email_invalid';
+    const EMAIL_IS_TEMPMAIL = 'error.email_is_tempmail';
+    const EMAIL_NOT_AVAILABLE = 'error.email_not_available';
+    const EMAIL_NOT_FOUND = 'error.email_not_found';
+
+    const LOGIN_REQUIRED = 'error.login_required';
+    const LOGIN_NOT_EXIST = 'error.login_not_exist';
+
+    const PASSWORD_REQUIRED = 'error.password_required';
+    const PASSWORD_INVALID = 'error.password_invalid';
+    /**
+     * TODO: На фронте с password_incorrect и password_invalid возникла неувязочка.
+     * Один возникает у формы входа и там уместно предлагать восстановление пароля.
+     * Другой возникает у паролезащищённой формы и там уже ничего предлагать не нужно.
+     * Но по факту это ведь одна и та же ошибка.
+     * @deprecated
+     */
+    const PASSWORD_INCORRECT = 'error.password_incorrect';
+    const PASSWORD_TOO_SHORT = 'error.password_too_short';
+
+    const KEY_REQUIRED = 'error.key_required';
+    const KEY_NOT_EXISTS = 'error.key_not_exists';
+    const KEY_EXPIRE = 'error.key_expire';
+
+    const ACCOUNT_NOT_ACTIVATED = 'error.account_not_activated';
+    const ACCOUNT_ALREADY_ACTIVATED = 'error.account_already_activated';
+    const ACCOUNT_CANNOT_RESEND_MESSAGE = 'error.account_cannot_resend_message';
+
+    const RECENTLY_SENT_MESSAGE = 'error.recently_sent_message';
+
+    const NEW_PASSWORD_REQUIRED = 'error.newPassword_required';
+    const NEW_RE_PASSWORD_REQUIRED = 'error.newRePassword_required';
+    const NEW_RE_PASSWORD_DOES_NOT_MATCH = self::RE_PASSWORD_DOES_NOT_MATCH;
+
+    const REFRESH_TOKEN_REQUIRED = 'error.refresh_token_required';
+    const REFRESH_TOKEN_NOT_EXISTS = 'error.refresh_token_not_exist';
+
+    const CAPTCHA_INVALID = 'error.captcha_invalid';
+
+    const RULES_AGREEMENT_REQUIRED = 'error.rulesAgreement_required';
+
+    const RE_PASSWORD_REQUIRED = 'error.rePassword_required';
+    const RE_PASSWORD_DOES_NOT_MATCH = 'error.rePassword_does_not_match';
+
+    const UNSUPPORTED_LANGUAGE = 'error.unsupported_language';
+
+    const SUBJECT_REQUIRED = 'error.subject_required';
+    const MESSAGE_REQUIRED = 'error.message_required';
+
+}

common/models/Account.php

@@ -1,6 +1,7 @@
 <?php
 namespace common\models;
 
+use common\helpers\Error as E;
 use common\components\UserPass;
 use common\validators\LanguageValidator;
 use Ely\Yii2\TempmailValidator;
@@ -57,22 +58,22 @@ class Account extends ActiveRecord {
     public function rules() {
         return [
             [['username'], 'filter', 'filter' => 'trim'],
-            [['username'], 'required', 'message' => 'error.username_required'],
+            [['username'], 'required', 'message' => E::USERNAME_REQUIRED],
             [['username'], 'string', 'min' => 3, 'max' => 21,
-                'tooShort' => 'error.username_too_short',
-                'tooLong' => 'error.username_too_long',
+                'tooShort' => E::USERNAME_TOO_SHORT,
+                'tooLong' => E::USERNAME_TOO_LONG,
             ],
             [['username'], 'match', 'pattern' => '/^[\p{L}\d-_\.!?#$%^&*()\[\]:;]+$/u',
-                'message' => 'error.username_invalid',
+                'message' => E::USERNAME_INVALID,
             ],
-            [['username'], 'unique', 'message' => 'error.username_not_available'],
+            [['username'], 'unique', 'message' => E::USERNAME_NOT_AVAILABLE],
 
             [['email'], 'filter', 'filter' => 'trim'],
-            [['email'], 'required', 'message' => 'error.email_required'],
-            [['email'], 'string', 'max' => 255, 'tooLong' => 'error.email_too_long'],
-            [['email'], 'email', 'checkDNS' => true, 'enableIDN' => true, 'message' => 'error.email_invalid'],
-            [['email'], TempmailValidator::class, 'message' => 'error.email_is_tempmail'],
-            [['email'], 'unique', 'message' => 'error.email_not_available'],
+            [['email'], 'required', 'message' => E::EMAIL_REQUIRED],
+            [['email'], 'string', 'max' => 255, 'tooLong' => E::EMAIL_TOO_LONG],
+            [['email'], 'email', 'checkDNS' => true, 'enableIDN' => true, 'message' => E::EMAIL_INVALID],
+            [['email'], TempmailValidator::class, 'message' => E::EMAIL_IS_TEMPMAIL],
+            [['email'], 'unique', 'message' => E::EMAIL_NOT_AVAILABLE],
 
             [['lang'], LanguageValidator::class],
             [['lang'], 'default', 'value' => 'en'],

common/validators/LanguageValidator.php

@@ -1,12 +1,13 @@
 <?php
 namespace common\validators;
 
+use common\helpers\Error as E;
 use Yii;
 use yii\validators\Validator;
 
 class LanguageValidator extends Validator {
 
-    public $message = 'error.unsupported_language';
+    public $message = E::UNSUPPORTED_LANGUAGE;
 
     protected function validateValue($value) {
         if (empty($value)) {

common/validators/PasswordValidate.php

@@ -1,6 +1,7 @@
 <?php
 namespace common\validators;
 
+use common\helpers\Error as E;
 use yii\validators\StringValidator;
 
 /**
@@ -10,6 +11,6 @@ class PasswordValidate extends StringValidator {
 
     public $min = 8;
 
-    public $tooShort = 'error.password_too_short';
+    public $tooShort = E::PASSWORD_TOO_SHORT;
 
 }