Markasjunk: Fix regression in jsevent driver #7361 (#7365)

plugins/markasjunk/drivers/jsevent.php

@@ -34,6 +34,12 @@ class markasjunk_jsevent
 
     public function init()
     {
+        $rcmail = rcmail::get_instance();
+
+        // only execute this code on page load
+        if ($rcmail->output->type != 'html')
+            return;
+
         $js_addition_spam_folders = json_encode($this->addition_spam_folders);
         $js_suspicious_folders    = json_encode($this->suspicious_folders);
 
@@ -65,7 +71,6 @@ rcmail.addEventListener('markasjunk-update', function(props) {
 });
 EOL;
 
-        $rcmail = rcmail::get_instance();
         $rcmail->output->add_script($script, 'docready');
     }