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

Jellyfin.Plugin.Seasonals/Web/marioday.js

@@ -51,8 +51,9 @@ function createMarioDay(container) {
     container.appendChild(wrapper);
     
     // Periodically throw out an 8-bit coin
-    setInterval(() => {
-        if (!document.querySelector('.marioday-container')) return;
+    const intervalId = setInterval(() => {
+        if (!document.body.contains(container)) { clearInterval(intervalId); return; }
+        if (container.style.display === 'none') return;
         const coin = document.createElement('div');
         coin.className = 'mario-coin';