fix

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

@@ -58,11 +58,13 @@ export function if_block(node, fn, elseif = false) {
 			offscreen_fragment = null;
 		}
 
+		if (pending_effect) {
 			if (condition) {
 				consequent_effect = pending_effect;
 			} else {
 				alternate_effect = pending_effect;
 			}
+		}
 
 		var current_effect = condition ? consequent_effect : alternate_effect;
 		var previous_effect = condition ? alternate_effect : consequent_effect;
@@ -114,7 +116,9 @@ export function if_block(node, fn, elseif = false) {
 			offscreen_fragment.append((target = document.createComment('')));
 		}
 
+		if (condition ? !consequent_effect : !alternate_effect) {
 			pending_effect = fn && branch(() => fn(target));
+		}
 
 		if (suspended) {
 			add_boundary_callback(boundary, commit);