fix: fix crash when navigating away from Latest Episodes during fetch

Gate latestEpisodesStore subscription by viewState to prevent async
fetch completions from updating displayedEpisodes after EpisodeList
is destroyed. Also use getEpisodeKey for stable {#each} keys.

Author: chhoumann

src/ui/PodcastView/EpisodeList.svelte

@@ -82,7 +82,7 @@
 		{#if episodes.length === 0 && !isLoading}
 			<p>No episodes found.</p>
 		{/if}
-		{#each episodes as episode (episode.url || episode.streamUrl || `${episode.title}-${episode.episodeDate ?? ""}`)}
+		{#each episodes as episode, index (getEpisodeKey(episode) ?? `${episode.title}-${episode.episodeDate ?? ""}-${index}`)}
 			{@const episodePlayed = isEpisodeFinished(episode, $playedEpisodes)}
 			{#if !$hidePlayedEpisodes || !episodePlayed}
 				<EpisodeListItem

src/ui/PodcastView/PodcastView.svelte

@@ -60,7 +60,7 @@
 
 	onMount(() => {
 		const unsubscribePlaylists = playlists.subscribe((pl) => {
-			displayedPlaylists = [$queue, $favorites, $localFiles, ...Object.values(pl)];
+			displayedPlaylists = [get(queue), get(favorites), get(localFiles), ...Object.values(pl)];
 		});
 
 		const unsubscribeSavedFeeds = savedFeeds.subscribe((storeValue) => {
@@ -78,11 +78,20 @@
 			}
 		});
 
+		let currentViewState = get(viewState);
+		const unsubscribeViewState = viewState.subscribe((vs) => {
+			currentViewState = vs;
+		});
+
 		const unsubscribeLatestEpisodes = latestEpisodesStore.subscribe(
 			(episodes) => {
 				latestEpisodes = episodes;
 
-				if (!selectedFeed && !selectedPlaylist) {
+				if (
+					currentViewState === ViewState.EpisodeList &&
+					!selectedFeed &&
+					!selectedPlaylist
+				) {
 					displayedEpisodes = currentSearchQuery
 						? searchEpisodes(currentSearchQuery, episodes)
 						: episodes;
@@ -92,6 +101,7 @@
 
 		return () => {
 			unsubscribeLatestEpisodes();
+			unsubscribeViewState();
 			unsubscribeSavedFeeds();
 			unsubscribePlaylists();
 		};
@@ -297,7 +307,7 @@
 		<EpisodeList
 			episodes={displayedEpisodes}
 			showThumbnails={!selectedFeed || !selectedPlaylist}
-			isLoading={isFetchingEpisodes}
+			isLoading={selectedFeed ? loadingFeeds.has(selectedFeed.title) : isFetchingEpisodes}
 			on:clickEpisode={handleClickEpisode}
 			on:contextMenuEpisode={handleContextMenuEpisode}
 			on:clickRefresh={handleClickRefresh}