php warnings

When running cron with drush I see multiple warnings
strtr() expects parameter 1 to be string, array given drupal.inc:72

The warnings go away if you change content_paywall.module line 139 from

watchdog('EntityMetadataWrapperException @msg', array('@msg' => $e->getMessage() . ': ' . $e->getTraceAsString()));
to
watchdog('EntityMetadataWrapperException @msg', array('@msg' => $e->getTraceAsString()));

Seems that $e->getMessage does not return a string. Maybe there is a better fix.