diff --git a/src/mapper/src/lib/components/offline/basemaps.svelte b/src/mapper/src/lib/components/offline/basemaps.svelte
index 8ff8fa991..f8af87e6a 100644
--- a/src/mapper/src/lib/components/offline/basemaps.svelte
+++ b/src/mapper/src/lib/components/offline/basemaps.svelte
@@ -1,20 +1,20 @@
 <script lang="ts">
-    import { onMount } from 'svelte';
+	import { onMount } from 'svelte';
 	import type { Snippet } from 'svelte';
-    import type { SlSelectEvent } from '@shoelace-style/shoelace/dist/events';
-    // FIXME this is a workaround to re-import, as using hot-select
-    // and hot-option prevents selection of values!
-    // TODO should raise an issue in hotosm/ui about this / test further
+	import type { SlSelectEvent } from '@shoelace-style/shoelace/dist/events';
+	// FIXME this is a workaround to re-import, as using hot-select
+	// and hot-option prevents selection of values!
+	// TODO should raise an issue in hotosm/ui about this / test further
 	import '@shoelace-style/shoelace/dist/components/select/select.js';
 	import '@shoelace-style/shoelace/dist/components/option/option.js';
 	import '@shoelace-style/shoelace/dist/components/button/button.js';
 
-    import type { Basemap } from '$lib/utils/basemaps';
-    import { getProjectBasemapStore } from '$store/common.svelte.ts';
+	import type { Basemap } from '$lib/utils/basemaps';
+	import { getProjectBasemapStore } from '$store/common.svelte.ts';
 	import { loadOnlinePmtiles, writeOfflinePmtiles } from '$lib/utils/basemaps';
 
 	interface Props {
-        projectId: number;
+		projectId: number;
 		children?: Snippet;
 	}
 
@@ -22,103 +22,100 @@
 	const basemapStore = getProjectBasemapStore();
 	let selectedBasemap: Basemap | null = $state(null);
 
-    // Reactive variables
+	// Reactive variables
 	let basemapsAvailable: boolean = $derived(basemapStore.projectBasemaps && basemapStore.projectBasemaps.length > 0);
 
 	onMount(() => {
-        basemapStore.refreshBasemaps(projectId);
+		basemapStore.refreshBasemaps(projectId);
 	});
 </script>
 
 <div class="flex flex-col items-center p-4 space-y-4">
-    <!-- Text above the basemap selector -->
-    <div class="text-center w-full">
-        <div class="font-bold text-lg font-barlow-medium">
-            <span class="mr-1">Manage Basemaps</span>
-        </div>
-    </div>
+	<!-- Text above the basemap selector -->
+	<div class="text-center w-full">
+		<div class="font-bold text-lg font-barlow-medium">
+			<span class="mr-1">Manage Basemaps</span>
+		</div>
+	</div>
 
-    <!-- Basemap selector -->
-    <div class="flex justify-center w-full max-w-sm">
-        {#if basemapsAvailable}
-            <!-- Note here we cannot two way bind:var to the web-component,
+	<!-- Basemap selector -->
+	<div class="flex justify-center w-full max-w-sm">
+		{#if basemapsAvailable}
+			<!-- Note here we cannot two way bind:var to the web-component,
             so use event instead -->
-            <sl-select
-                placeholder="Select a basemap"
-                onsl-change={(event: SlSelectEvent) => {
-                    const selectedId = event.originalTarget.value
-                    selectedBasemap = basemapStore.projectBasemaps?.find((basemap: Basemap) => basemap.id === selectedId) || null
-                }}
-            >
-                {#each basemapStore.projectBasemaps as basemap}
-                {#if basemap.status === "SUCCESS"}
-                    <sl-option value={basemap.id}>
-                        {basemap.tile_source} {basemap.format}
-                    </sl-option>
-                {/if}
-                {/each}
-            </sl-select>
-        {:else}
-            <div class="text-center w-full">
-                <div class="text-sm font-barlow-medium">
-                    There are no basemaps available for this project.
-                </div>
-                <div class="text-sm font-barlow-medium pt-2">
-                    Please ask the project manager to create basemaps.
-                </div>
-            </div>
-        {/if}
-    </div>
+			<sl-select
+				placeholder="Select a basemap"
+				onsl-change={(event: SlSelectEvent) => {
+					const selectedId = event.target.value;
+					selectedBasemap = basemapStore.projectBasemaps?.find((basemap: Basemap) => basemap.id === selectedId) || null;
+				}}
+			>
+				{#each basemapStore.projectBasemaps as basemap}
+					{#if basemap.status === 'SUCCESS'}
+						<sl-option value={basemap.id}>
+							{basemap.tile_source}
+							{basemap.format}
+						</sl-option>
+					{/if}
+				{/each}
+			</sl-select>
+		{:else}
+			<div class="text-center w-full">
+				<div class="text-sm font-barlow-medium">There are no basemaps available for this project.</div>
+				<div class="text-sm font-barlow-medium pt-2">Please ask the project manager to create basemaps.</div>
+			</div>
+		{/if}
+	</div>
 
-    <!-- Load baselayer & download to OPFS buttons -->
-    {#if selectedBasemap && selectedBasemap.format === 'pmtiles' }
-        <hot-button
-            onclick={() => loadOnlinePmtiles(selectedBasemap.url)}
-            onkeydown={(e: KeyboardEvent) => {
-                e.key === 'Enter' && loadOnlinePmtiles(selectedBasemap.url);
-            }}
-            role="button"
-            tabindex="0"
-            size="small"
-            class="secondary w-full max-w-[200px]"
-        >
-            <hot-icon slot="prefix" name="download" class="!text-[1rem] text-[#b91c1c] cursor-pointer duration-200"
-            ></hot-icon>
-            <span class="font-barlow-medium text-base uppercase">Show On Map</span>
-        </hot-button>
+	<!-- Load baselayer & download to OPFS buttons -->
+	{#if selectedBasemap && selectedBasemap.format === 'pmtiles'}
+		<hot-button
+			onclick={() => loadOnlinePmtiles(selectedBasemap?.url)}
+			onkeydown={(e: KeyboardEvent) => {
+				e.key === 'Enter' && loadOnlinePmtiles(selectedBasemap?.url);
+			}}
+			role="button"
+			tabindex="0"
+			size="small"
+			class="secondary w-full max-w-[200px]"
+		>
+			<hot-icon slot="prefix" name="download" class="!text-[1rem] text-[#b91c1c] cursor-pointer duration-200"
+			></hot-icon>
+			<span class="font-barlow-medium text-base uppercase">Show On Map</span>
+		</hot-button>
 
-        <hot-button
-            onclick={() => writeOfflinePmtiles(projectId, selectedBasemap.url)}
-            onkeydown={(e: KeyboardEvent) => {
-                e.key === 'Enter' && writeOfflinePmtiles(projectId, selectedBasemap.url);
-            }}
-            role="button"
-            tabindex="0"
-            size="small"
-            class="secondary w-full max-w-[200px]"
-        >
-            <hot-icon slot="prefix" name="download" class="!text-[1rem] text-[#b91c1c] cursor-pointer duration-200"
-            ></hot-icon>
-            <span class="font-barlow-medium text-base uppercase">Store Offline</span>
-        </hot-button>
+		<hot-button
+			onclick={() => writeOfflinePmtiles(projectId, selectedBasemap?.url)}
+			onkeydown={(e: KeyboardEvent) => {
+				e.key === 'Enter' && writeOfflinePmtiles(projectId, selectedBasemap?.url);
+			}}
+			role="button"
+			tabindex="0"
+			size="small"
+			class="secondary w-full max-w-[200px]"
+		>
+			<hot-icon slot="prefix" name="download" class="!text-[1rem] text-[#b91c1c] cursor-pointer duration-200"
+			></hot-icon>
+			<span class="font-barlow-medium text-base uppercase">Store Offline</span>
+		</hot-button>
 
-    <!-- Download Mbtiles Button -->
-    {:else if selectedBasemap && selectedBasemap.format === 'mbtiles' }
-        <hot-button
-            onclick={() => window.open(selectedBasemap.url)}
-            onkeydown={(e: KeyboardEvent) => {
-                e.key === 'Enter' && window.open(selectedBasemap.url);
-            }}
-            role="button"
-            tabindex="0"
-            size="small"
-            class="secondary w-full max-w-[200px]"
-        >
-            <hot-icon slot="prefix" name="download" class="!text-[1rem] text-[#b91c1c] cursor-pointer duration-200"
-            ></hot-icon>
-            <span class="font-barlow-medium text-base uppercase">Download MBTiles</span>
-        </hot-button>
-    {/if}
+		<!-- Download Mbtiles Button -->
+	{:else if selectedBasemap && selectedBasemap.format === 'mbtiles'}
+		<hot-button
+			onclick={() => window.open(selectedBasemap?.url)}
+			onkeydown={(e: KeyboardEvent) => {
+				e.key === 'Enter' && window.open(selectedBasemap?.url);
+			}}
+			role="button"
+			tabindex="0"
+			size="small"
+			class="secondary w-full max-w-[200px]"
+		>
+			<hot-icon slot="prefix" name="download" class="!text-[1rem] text-[#b91c1c] cursor-pointer duration-200"
+			></hot-icon>
+			<span class="font-barlow-medium text-base uppercase">Download MBTiles</span>
+		</hot-button>
+	{/if}
 
-    {@render children?.()}
+	{@render children?.()}
 </div>
diff --git a/src/mapper/src/lib/utils/basemaps.ts b/src/mapper/src/lib/utils/basemaps.ts
index 485ec106d..f300ae40b 100644
--- a/src/mapper/src/lib/utils/basemaps.ts
+++ b/src/mapper/src/lib/utils/basemaps.ts
@@ -38,7 +38,7 @@ export async function getBasemapList(projectId: number): Promise<Basemap[]> {
 	}
 }
 
-export async function loadOnlinePmtiles(url: string | null) {
+export async function loadOnlinePmtiles(url: string | undefined) {
 	if (!url) return;
 
 	const pmtilesUrl = `pmtiles://${url}`;
@@ -60,7 +60,7 @@ export async function loadOfflinePmtiles(projectId: number) {
 	basemapStore.setProjectPmtilesUrl(pmtilesUrl);
 }
 
-async function downloadBasemap(url: string | null): Promise<ArrayBuffer> {
+async function downloadBasemap(url: string | undefined): Promise<ArrayBuffer> {
 	let basemapData: ArrayBuffer = new ArrayBuffer(0);
 
 	if (!url) return basemapData;
@@ -87,7 +87,7 @@ async function downloadBasemap(url: string | null): Promise<ArrayBuffer> {
 	}
 }
 
-export async function writeOfflinePmtiles(projectId: number, url: string | null) {
+export async function writeOfflinePmtiles(projectId: number, url: string | undefined) {
 	const data = await downloadBasemap(url);
 
 	// Copy to OPFS filesystem for offline use