simplifyFileInError example

// Display the message if the current error reporting level allows this type     // of message to be displayed, and unconditionally in update.php.     $message = '';
    if ($this->isErrorDisplayable($error)) {
      // If error type is 'User notice' then treat it as debug information       // instead of an error message.       if ($error['%type'] == 'User notice') {
        $error['%type'] = 'Debug';
      }

      $error = $this->simplifyFileInError($error);

      unset($error['backtrace'], $error['exception'], $error['severity_level']);

      if (!$this->isErrorLevelVerbose()) {
        // Without verbose logging, use a simple message.
        // We use \Drupal\Component\Render\FormattableMarkup directly here,         // rather than use t() since we are in the middle of error handling, and         // we don't want t() to cause further errors.         $message = new FormattableMarkup(Error::DEFAULT_ERROR_MESSAGE, $error);
      }