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

Jellyfin.Plugin.Seasonals/Web/easter.js

@@ -245,6 +245,7 @@ function animateRabbit(rabbit) {
 
             isAnimating = false;
             rabbitTimeout = setTimeout(() => {
+                if (!document.body.contains(rabbit)) return;
                 animateRabbit(document.querySelector('#rabbit'));
             }, restTime);
             return;