create correct parent-child relationship between if block and its branches

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

@@ -127,14 +127,13 @@ export function if_block(anchor_node, condition_fn, consequent_fn, alternate_fn)
 
 				has_mounted = true;
 			}
-		},
-		block,
-		false
-	);
 
-	// Managed effect
-	consequent_effect = render_effect(
-		(/** @type {any} */ _, /** @type {import('#client').Effect | null} */ consequent_effect) => {
+			// create these here so they have the correct parent/child relationship
+			consequent_effect ??= render_effect(
+				(
+					/** @type {any} */ _,
+					/** @type {import('#client').Effect | null} */ consequent_effect
+				) => {
 					const result = block.v;
 
 					if (!result && consequent_dom !== null) {
@@ -159,8 +158,7 @@ export function if_block(anchor_node, condition_fn, consequent_fn, alternate_fn)
 			);
 			block.ce = consequent_effect;
 
-	// Managed effect
-	alternate_effect = render_effect(
+			alternate_effect ??= render_effect(
 				(/** @type {any} */ _, /** @type {import('#client').Effect | null} */ alternate_effect) => {
 					const result = block.v;
 
@@ -188,6 +186,10 @@ export function if_block(anchor_node, condition_fn, consequent_fn, alternate_fn)
 				true
 			);
 			block.ae = alternate_effect;
+		},
+		block,
+		false
+	);
 
 	if_effect.ondestroy = () => {
 		if (consequent_dom !== null) {

packages/svelte/src/internal/client/runtime.js

@@ -786,25 +786,11 @@ export function mark_subtree_inert(signal, inert, visited_blocks = new Set()) {
 		if (!inert && (flags & CLEAN) === 0) {
 			schedule_effect(signal, false);
 		}
-		// Nested if block effects
+
 		const block = signal.block;
 		if (block !== null && !visited_blocks.has(block)) {
 			visited_blocks.add(block);
-			const type = block.t;
-			if (type === IF_BLOCK) {
-				const condition_effect = block.e;
-				if (condition_effect !== null && block !== current_block) {
-					mark_subtree_inert(condition_effect, inert, visited_blocks);
-				}
-				const consequent_effect = block.ce;
-				if (consequent_effect !== null && block.v) {
-					mark_subtree_inert(consequent_effect, inert, visited_blocks);
-				}
-				const alternate_effect = block.ae;
-				if (alternate_effect !== null && !block.v) {
-					mark_subtree_inert(alternate_effect, inert, visited_blocks);
-				}
-			} else if (type === EACH_BLOCK) {
+			if (block.t === EACH_BLOCK) {
 				const items = block.v;
 				for (let { e: each_item_effect } of items) {
 					if (each_item_effect !== null) {