Invalid argument foreach() in line 168 of display-render.inc

I attempted to create a new panel node. I filled the two required fields with some gibberish (randomly typed numbers), and hit preview on the edit page.

warning: Invalid argument supplied for foreach() in C:\wamp\www\drupal-6.2\sites\all\modules\panels\includes\display-render.inc on line 168.

I tried to edit an already existing panel node, by just editing it and then hitting preview on the edit page. Same error. Nothing in the php log.