function onList( error, list ) {
		if ( error ) {
			debug( 'Encountered an error when resolving namespaces: %s', error.message );
			return done( error );
		}
		if ( list.length === 0 ) {
			debug( 'Unable to resolve any namespaces.' );
			return done( null, [] );
		}
		debug( 'Successfully resolved %d namespaces: %s', list.length, list.join( ',' ) );

		debug( 'Resolving main entry points...' );
		resolve( list, dir, onResolve );
	}
Callback invoked upon resolving a list of namespaces.

@private
@param {(Error|null)} error - error object
@param {(EmptyArray|StringArray)} list - list of namespaces
@returns {void}