Fix file picker types issue

Author: shoaib0300

src/EventListener/Mcw/TinyMce.php

@@ -46,7 +46,7 @@ public function executeEvent(GetTinyMceStringEvent $event)
         $table   = $event->getTableName();
         $fieldId = $event->getFieldId();
 
-        list ($file, $type) = explode('|', $field['eval']['rte'], 2);
+        list($file, $type) = explode('|', $field['eval']['rte'], 2) + [null, null];
 
         $fileBrowserTypes = array();
         // Since we don't know if this is the right call for other versions of contao
@@ -63,7 +63,7 @@ public function executeEvent(GetTinyMceStringEvent $event)
         $objTemplate                   = new BackendTemplate('be_' . $file);
         $objTemplate->selector         = 'ctrl_' . $fieldId;
         $objTemplate->type             = $type;
-        $objTemplate->fileBrowserTypes = $fileBrowserTypes;
+        $objTemplate->fileBrowserTypes =  json_encode($fileBrowserTypes);
         $objTemplate->source           = $table . '.' . $fieldId;
 
         // Deprecated since Contao 4.0, to be removed in Contao 5.0