function onWrite( error ) {
			if ( error ) {
				debug( 'Error encountered when attempting to write an SVG to file: %s', error.message );
				return done( error );
			}
			debug( 'SVG successfully written to file.' );
			done();
		}
Callback invoked upon writing an SVG to file.

@param {(Error|null)} error - error object
@returns {void}