How to use the @here/harp-utils.assertExists function in @here/harp-utils

addPois(tile: Tile, decodedTile: DecodedTile): void {
        const poiGeometries = assertExists(decodedTile.poiGeometries);
        const worldOffsetX = tile.computeWorldOffsetX();

        for (const poiGeometry of poiGeometries) {
            assert(poiGeometry.technique !== undefined);
            const techniqueIndex = assertExists(poiGeometry.technique);
            const technique = decodedTile.techniques[techniqueIndex];

            if (
                technique.enabled === false ||
                (!isLineMarkerTechnique(technique) && !isPoiTechnique(technique))
            ) {
                continue;
            }

            // The POI may be in the data, and there may be a Technique, but the technique may
            // specify to not show it.

addPois(tile: Tile, decodedTile: DecodedTile): void {
        const poiGeometries = assertExists(decodedTile.poiGeometries);
        const worldOffsetX = tile.computeWorldOffsetX();

        for (const poiGeometry of poiGeometries) {
            assert(poiGeometry.technique !== undefined);
            const techniqueIndex = assertExists(poiGeometry.technique);
            const technique = decodedTile.techniques[techniqueIndex];

            if (
                technique.enabled === false ||
                (!isLineMarkerTechnique(technique) && !isPoiTechnique(technique))
            ) {
                continue;
            }

            // The POI may be in the data, and there may be a Technique, but the technique may
            // specify to not show it.
            if (technique.showOnMap === false) {
                continue;
            }

            const positions = new THREE.BufferAttribute(