_getTotal( data ) {
		// try to get the "total" metadata value
		const { fetchMetadataPath } = this;
		if ( !data || !fetchMetadataPath ) {
			return null;
		}
		const total = get( data, fetchMetadataPath );
		const parsed = Number( total );
		if ( isNaN( parsed ) || parsed < 1 ) {
			return null;
		}
		return parsed;
	}
@param {Object} data
@returns {(number|null)}