updated the GoogleMap.svelte for dedupe, optional chaining

src/components/map/GoogleMap.svelte

@@ -55,38 +55,30 @@
 
 	async function loadStopsAndAddMarkers(lat, lng) {
 		const json = await loadStopsForLocation(lat, lng);
-		const stops = json.data.list;
-		allStops = [...allStops, ...stops];
+		const newStops = json.data.list;
+
+		allStops = [...new Map([...allStops, ...newStops].map((stop) => [stop.id, stop])).values()];
 
 		clearAllMarkers();
 
 		if (showRoute && selectedRoute) {
 			const stopsToShow = allStops.filter((s) => s.routeIds.includes(selectedRoute.id));
 			stopsToShow.forEach((s) => addMarker(s));
 		} else {
-			stops.forEach((s) => addMarker(s));
+			newStops.forEach((s) => addMarker(s));
 		}
 	}
 
 	function clearAllMarkers() {
 		markers.forEach(({ marker, overlay, element }) => {
-			if (marker) {
-				marker.setMap(null);
-			}
+			marker?.setMap(null);
+
 			if (overlay) {
-				if (overlay.map) {
-					overlay.map = null;
-				}
-				if (overlay.draw) {
-					overlay.draw = () => {};
-				}
-				if (overlay.onRemove) {
-					overlay.onRemove();
-				}
-			}
-			if (element && element.parentNode) {
-				element.parentNode.removeChild(element);
+				overlay.setMap(null);
+				overlay.draw = () => {};
+				overlay.onRemove?.();
 			}
+			element?.parentNode?.removeChild(element);
 		});
 		markers = [];
 	}
@@ -147,9 +139,7 @@
 			this.getPanes().overlayMouseTarget.appendChild(container);
 		};
 		overlay.onRemove = function () {
-			if (container.parentNode) {
-				container.parentNode.removeChild(container);
-			}
+			container?.parentNode?.removeChild(container);
 		};
 		markers.push({ s, marker, overlay, element: container });
 	}