fix: Don't attempt to create object url when not blob

src/Javascript/UI/artwork.ts

···
 // 🛠️
 
 
-export function albumCover(coverKey: string): Promise<Blob | null> {
+export function albumCover(coverKey: string): Promise<Blob | "TRIED" | null> {
   return db().getItem(`coverCache.${coverKey}`)
 }
 

src/Javascript/UI/audio.ts

···
   if (coverPrep) {
     const blob = await albumCover(coverPrep.cacheKey)
 
-    artwork = blob
+    artwork = blob && typeof blob !== "string"
       ? [{
         src: URL.createObjectURL(blob),
         type: blob.type