Do I have any way of knowing about errors or potential problems when designing my Customer Portal pages?

Environment:

Customer Portal
Oracle B2C Service, all versions

Resolution:

The Customer Portal development area includes messages regarding important errors, warmings and notifications. From the Customer Portal admin page (i.e. https://<vhostname>.custhelp.com/ci/admin) > select View Development Area. Select the "Customer Portal Development Area" bar at the top to expand the Errors and Warnings listing. 

Collapsed notification window (click to enlarge)

These messages are meant to give developers useful debugging and widget information:

Expanded notification window (click to enlarge)

Errors and warnings include those generated from PHP and JavaScript, and widget information includes the notification that a page set includes deprecated widgets.

For more information on handling compatibility warning messages, refer to current Documentation for Oracle B2C Service Products.