Enable PicoDeprecated if no plugins are loaded

plugins/00-PicoDeprecated.php

@@ -69,6 +69,7 @@ class PicoDeprecated extends AbstractPicoPlugin
      */
     public function onPluginsLoaded(&$plugins)
     {
+        if (!empty($plugins)) {
             foreach ($plugins as $plugin) {
                 if (!is_a($plugin, 'PicoPluginInterface')) {
                     // the plugin doesn't implement PicoPluginInterface; it uses deprecated events
@@ -79,6 +80,14 @@ class PicoDeprecated extends AbstractPicoPlugin
                     break;
                 }
             }
+        } else {
+            // no plugins were found, so it actually isn't necessary to call deprecated events
+            // anyway, this plugin also ensures compatibility apart from events used by old plugins,
+            // so enable PicoDeprecated if it hasn't be explicitly enabled/disabled yet
+            if (!$this->isStatusChanged()) {
+                $this->setEnabled(true, true, true);
+            }
+        }
 
         if ($this->isEnabled()) {
             $this->triggerEvent('plugins_loaded');