Although it is not required, we recommend that you install Xdebug if you plan to develop with PHP. It will make debugging, testing and profiling much easier. Installation of Xdebug is quite straightforward, we personally use the CVS version and just followed the instructions on the Xdebug website.

There is one setting though which you should add to your php.ini file which controls the number of nested calls which are allowed. Due to some unit tests which check for infinite loops, you'll have to raise that limit to something like 500:

xdebug.max_nesting_level = 500