[4.3] check of invalid json 'joomla.asset.json' (joomla#41135)

Author: heelc29

administrator/components/com_templates/src/Model/TemplateModel.php

@@ -959,7 +959,7 @@ public function save($data)
  $data['source'] = str_replace(["\r\n", "\r"], "\n", $data['source']);
 
  // If the asset file for the template ensure we have valid template so we don't instantly destroy it
- if ($fileName === '/joomla.asset.json' && json_decode($data['source']) === null) {
+ if (str_ends_with($fileName, '/joomla.asset.json') && json_decode($data['source']) === null) {
  $this->setError(Text::_('COM_TEMPLATES_ERROR_ASSET_FILE_INVALID_JSON'));
 
  return false;