- satisfying styleci

- cleared the merge conflict in the phpdoc
- changed some string class names to use ::class

src/Admin/AdminServiceProvider.php

@@ -11,14 +11,11 @@
 
 namespace Flarum\Admin;
 
+use Flarum\Admin\Listener\CheckCustomLessFormat;
 use Flarum\Admin\Middleware\RequireAdministrateAbility;
 use Flarum\Event\ConfigureMiddleware;
 use Flarum\Extension\Event\Disabled;
 use Flarum\Extension\Event\Enabled;
-use Flarum\Core\Listener\CheckCustomLessFormat;
-use Flarum\Event\ExtensionWasDisabled;
-use Flarum\Event\ExtensionWasEnabled;
-use Flarum\Event\SettingWasSet;
 use Flarum\Foundation\AbstractServiceProvider;
 use Flarum\Http\Middleware\AuthenticateWithSession;
 use Flarum\Http\Middleware\DispatchRoute;

src/Admin/Listener/CheckCustomLessFormat.php

@@ -0,0 +1,43 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * (c) Toby Zerner <toby.zerner@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Flarum\Admin\Listener;
+
+use Flarum\Foundation\ValidationException;
+use Flarum\Settings\Event\Serializing;
+use Illuminate\Contracts\Events\Dispatcher;
+use Less_Exception_Parser;
+use Less_Parser;
+
+class CheckCustomLessFormat
+{
+    public function subscribe(Dispatcher $events)
+    {
+        $events->listen(Serializing::class, [$this, 'check']);
+    }
+
+    public function check(Serializing $event)
+    {
+        if ($event->key === 'custom_less') {
+            $parser = new Less_Parser();
+
+            try {
+                // Check the custom less format before saving
+                // Variables names are not checked, we would have to set them and call getCss() to check them
+                $parser->parse($event->value);
+            } catch (Less_Exception_Parser $e) {
+                throw new ValidationException([
+                    'custom_less' => $e->getMessage(),
+                ]);
+            }
+        }
+    }
+}