Fix PHP warning when defaults.inc.php is not readable

program/include/rcmail_install.php

@@ -573,21 +573,25 @@ class rcmail_install
     $plugins = array();
     $plugin_dir = INSTALL_PATH . 'plugins/';
 
-    foreach (glob($plugin_dir . '*') as $path) 
+    foreach (glob($plugin_dir . '*') as $path) {
-    {
+      if (!is_dir($path)) {
+        continue;
+      }
 
-      if (is_dir($path) && is_readable($path.'/composer.json'))
+      if (is_readable($path.'/composer.json')) {
-      {
         $file_json   = json_decode(file_get_contents($path.'/composer.json'));
         $plugin_desc = $file_json->description ?: 'N/A';
       }
-      else
+      else {
-      {
         $plugin_desc = 'N/A';
       }
 
       $name      = substr($path, strlen($plugin_dir));
-      $plugins[] = array('name' => $name, 'desc' => $plugin_desc, 'enabled' => in_array($name, $this->config['plugins']));
+      $plugins[] = array(
+        'name'    => $name,
+        'desc'    => $plugin_desc,
+        'enabled' => in_array($name, (array) $this->config['plugins'])
+      );
     }
 
     return $plugins;