I had a situation with the Rails plugin[1] where I received the following message when running rake:

config/facebook.yml could not be loaded.

This message was not very informative of the root cause, so while debugging I added additional information to the message,
like so:

/home/fernando/tmp/test/config/facebook.yml could not be loaded (uninitialized constant YAML).

I think this additional information can benefit other users and it will cause no harm to the plugin, so I'm attaching
a patch.

[1] For a description of the original situation see
http://groups.google.com/group/rfacebook/browse_thread/thread/d1f275474f316f77