Consolidate Last.fm fallback cover handling

lib/last_fm.ex

@@ -76,5 +76,11 @@ defmodule LastFm do
     "https://www.last.fm/api/auth/?api_key=" <> last_fm_config.api_key
   end
 
+  @last_fm_fallback_cover_url "https://lastfm.freetls.fastly.net/i/u/64s/2a96cbd8b46e442fc41c2b86b821562f.png"
+
+  def fallback_cover?(cover_url) do
+    cover_url == @last_fm_fallback_cover_url
+  end
+
   defp last_fm_config, do: LastFm.Config.resolve(:music_library)
 end

lib/music_library_web/live/stats_live/index.ex

@@ -150,10 +150,8 @@ defmodule MusicLibraryWeb.StatsLive.Index do
     |> DateTime.to_iso8601()
   end
 
-  @last_fm_fallback_cover_url "https://lastfm.freetls.fastly.net/i/u/64s/2a96cbd8b46e442fc41c2b86b821562f.png"
-
   defp track_or_album_cover_url(track_or_album, cover_hash) do
-    if track_or_album.cover_url == @last_fm_fallback_cover_url do
+    if LastFm.fallback_cover?(track_or_album.cover_url) do
       payload =
         Transform.new(hash: cover_hash, width: 96)
         |> Transform.encode!()

lib/music_library_web/live/stats_live/top_albums.ex

@@ -191,10 +191,8 @@ defmodule MusicLibraryWeb.StatsLive.TopAlbums do
     end
   end
 
-  @last_fm_fallback_cover_url "https://lastfm.freetls.fastly.net/i/u/64s/2a96cbd8b46e442fc41c2b86b821562f.png"
-
   defp cover_url(album) do
-    if album.cover_url == @last_fm_fallback_cover_url do
+    if LastFm.fallback_cover?(album.cover_url) do
       payload =
         Transform.new(hash: album.cover_hash, width: 96)
         |> Transform.encode!()