Add checks for container presence in animation functions to prevent errors when elements are removed from the DOM [skip ci]

Jellyfin.Plugin.Seasonals/Web/friday13.js

@@ -61,12 +61,12 @@ function createFriday13(container) {
                 cat.parentNode.removeChild(cat);
             }
             // Respawn with random delay between 5 to 25 seconds
-            setTimeout(spawnCat, Math.random() * 20000 + 5000);
+            setTimeout(() => { if (document.body.contains(container)) spawnCat(); }, Math.random() * 20000 + 5000);
         }, (catWalkDurationSeconds * 1000) + 500); // Wait for duration + 500ms safety margin
     }
     
     // Initial spawn with random delay
-    setTimeout(spawnCat, Math.random() * 5000);
+    setTimeout(() => { if (document.body.contains(container)) spawnCat(); }, Math.random() * 5000);
 }
 
 function initializeFriday13() {