On some PHP sites that using PHP includes and make MySQL calls, we have seen
the following:

When a user edits a page, they see a PHP error saying that the connection to
the MySQL database couldn't be made.

Why in the world is Contribute executing PHP code in an include? To get
around this, we've had to add code around the SQL connection which simply
echoes (with PHP) "unable to connect" if a connection can not be made.

But, on other sites, we've used echo to see if PHP is indeed executing in edit
mode of Contribute, but it doesn't echo.