chore: tweak each block runtime logic

packages/svelte/src/internal/client/dom/blocks/each.js

@@ -394,11 +394,12 @@ function reconcile(array, state, anchor, render_fn, flags, get_key) {
 
 	const to_destroy = Array.from(seen);
 
-	while (current) {
+	while (current !== null) {
 		to_destroy.push(current);
 		current = current.next;
 	}
 
+	if (to_destroy.length > 0) {
 		var controlled_anchor = (flags & EACH_IS_CONTROLLED) !== 0 && length === 0 ? anchor : null;
 
 		if (is_animated) {
@@ -419,6 +420,7 @@ function reconcile(array, state, anchor, render_fn, flags, get_key) {
 				link(item.prev, item.next);
 			}
 		});
+	}
 
 	if (is_animated) {
 		effect(() => {