注册时防止昵称重复

@@ -125,11 +125,15 @@ class Auth
      */
     public function register($username, $password, $email = '', $mobile = '', $extend = [])
     {
-        // 检测用户名或邮箱、手机号是否存在
+        // 检测用户名、昵称、邮箱、手机号是否存在
         if (User::getByUsername($username)) {
             $this->setError('Username already exist');
             return false;
         }
+        if (User::getByNickname($username)) {
+            $this->setError('Nickname already exist');
+            return false;
+        }
         if ($email && User::getByEmail($email)) {
             $this->setError('Email already exist');
             return false;

@@ -29,6 +29,7 @@ return [
     'Email is incorrect'                    => '邮箱格式不正确',
     'Mobile is incorrect'                   => '手机格式不正确',
     'Username already exist'                => '用户名已经存在',
+    'Nickname already exist'                => '昵称已经存在',
     'Email already exist'                   => '邮箱已经存在',
     'Mobile already exist'                  => '手机号已经存在',
     'Username is incorrect'                 => '用户名不正确',