Put stream in downloading map on click rather than on dl start

prevents network issue race conditions

src/lib/streamCache.svelte.ts

@@ -18,6 +18,10 @@ if (browser) {
 }
 
 export async function download(stream: StreamSummary) {
+	if (downloading.has(stream.id) || cached.has(stream.id)) return;
+	downloading.set(stream.id, 0);
+
+	try {
 		const res = await fetch(`/media/tracks/${stream.filename}`);
 		if (!res.ok || !res.body) throw new Error('Download failed');
 
@@ -26,8 +30,6 @@ export async function download(stream: StreamSummary) {
 		const chunks: Uint8Array[] = [];
 		let received = 0;
 
-	downloading.set(stream.id, 0);
-
 		while (true) {
 			const { done, value } = await reader.read();
 			if (done) break;
@@ -42,8 +44,10 @@ export async function download(stream: StreamSummary) {
 		await writable.write(new Blob(chunks));
 		await writable.close();
 
-	downloading.delete(stream.id);
 		cached.add(stream.id);
+	} finally {
+		downloading.delete(stream.id);
+	}
 }
 
 export async function remove(streamId: string) {