Recently edited resources crashes if createdon is 0

[BobRay]

Bug report

Summary

Some resources installed by extras can have a createdon value of 0. In MODX 3.0.4, this crashes the Recently edited widget with a big error message with a red background.

This happens with display_errors on or off.

This does not happen in MODX 3.0.1 or MODX 2.8.5

Step to reproduce

Set a Resource createdon value to 0 in the DB
Reload a dashboard containing the Recently Edited Resources Widget