Fix PHP error when adding a new user with email notification enabled

ChangeLog

@@ -10,6 +10,7 @@ Bug fixes:
 * Loading cs_CZ locale display the wrong language in datetime picker
 * Datepicker is closed unexpectedly on blur event
 * Fix bug in daily project summary CSV export
+* Fix PHP error when adding a new user with email notification enabled
 
 Version 1.0.20
 --------------

app/Controller/User.php

@@ -3,6 +3,7 @@
 namespace Kanboard\Controller;
 
 use Kanboard\Model\NotificationType;
+use Kanboard\Notification\Mail as MailNotification;
 
 /**
  * User controller
@@ -95,7 +96,7 @@ class User extends Base
                 $this->projectPermission->addMember($project_id, $user_id);
 
                 if (! empty($values['notifications_enabled'])) {
-                    $this->userNotificationType->saveSelectedTypes($user_id, array(NotificationType::TYPE_EMAIL));
+                    $this->userNotificationType->saveSelectedTypes($user_id, array(MailNotification::TYPE));
                 }
 
                 $this->session->flash(t('User created successfully.'));

app/Notification/Mail.php

@@ -16,6 +16,13 @@ use Kanboard\Model\Subtask;
  */
 class Mail extends Base implements NotificationInterface
 {
+    /**
+     * Notification type
+     *
+     * @var string
+     */
+    const TYPE = 'email';
+
     /**
      * Send notification to a user
      *

app/Notification/Web.php

@@ -12,6 +12,13 @@ use Kanboard\Core\Base;
  */
 class Web extends Base implements NotificationInterface
 {
+    /**
+     * Notification type
+     *
+     * @var string
+     */
+    const TYPE = 'web';
+
     /**
      * Send notification to a user
      *

app/ServiceProvider/ClassProvider.php

@@ -14,6 +14,8 @@ use Kanboard\Core\Tool;
 use Kanboard\Core\Http\Client as HttpClient;
 use Kanboard\Model\UserNotificationType;
 use Kanboard\Model\ProjectNotificationType;
+use Kanboard\Notification\Mail as MailNotification;
+use Kanboard\Notification\Web as WebNotification;
 
 class ClassProvider implements ServiceProviderInterface
 {
@@ -141,8 +143,8 @@ class ClassProvider implements ServiceProviderInterface
 
         $container['userNotificationType'] = function ($container) {
             $type = new UserNotificationType($container);
-            $type->setType('email', t('Email'), '\Kanboard\Notification\Mail');
-            $type->setType('web', t('Web'), '\Kanboard\Notification\Web');
+            $type->setType(MailNotification::TYPE, t('Email'), '\Kanboard\Notification\Mail');
+            $type->setType(WebNotification::TYPE, t('Web'), '\Kanboard\Notification\Web');
             return $type;
         };