Update MapTab component

frontend/src/lib/components/tabs/MapTab.svelte

@@ -10,10 +10,13 @@
 	let latitude;
 	let longitude;
 	let accuracy;
-	
-	const loadWorker = async () => {
+	const errorMessage = "Geolocation not available";
+	let errored = false;
+
+	const watchPosition = async () => {
         if (!("geolocation" in navigator)) {
-            return;
+			errored = true;
+			throw new Error(errorMessage)
         }
 
         const options = {
@@ -45,7 +48,7 @@
     };
 
 	onMount(async () => {
-		await loadWorker();
+		await watchPosition();
 		leaflet = await import('leaflet');
 		layerGroup = leaflet.layerGroup();
 
@@ -75,8 +78,11 @@
 		}
 	});
 </script>
-
+{#if !errored}
 <div id="map" in:fade bind:this={mapElement} />
+{:else}
+{errorMessage}
+{/if}
 
 <style>
 	@import 'leaflet/dist/leaflet.css';