Print error when readdirSync fails while watching
Print error when readdirSync fails while watching

We continue to ignore this error (as it can happen when the file system
changes suddenly), but it's perhaps useful to print the error, because
this can also happen if we run out of file handles.

ixisystems/broccoli,jnicklas/broccoli,ember-cli/broccoli,rwjblue/broccoli,ember-cli/broccoli,gabesoft/broccoli,broccolijs/broccoli,osxi/broccoli,broccolijs/broccoli,osxi/broccoli,broccolijs/broccoli,ember-cli/broccoli,ixisystems/broccoli,osxi/broccoli,gabesoft/broccoli,gabesoft/broccoli,broccolijs/broccoli