fix: push renderer in effects even if it's `null`

This is needed because effects record the renderer they were created with.
But if we interlieve a DOM renderer with a Custom one, current_renderer
could be a custom one when the effect reruns and if we don't push `null`
it will use the custom_renderer methods instead of the DOM ones.

packages/svelte/src/internal/client/custom-renderer/state.js

@@ -20,8 +20,9 @@ export function set_renderer(value) {
  */
 export function push_renderer(value) {
 	var previous_hydrating = hydrating;
+	var should_disable_hydration = hydrating && value != null;
 	// this is to allow hydration code to treeshake
-	if (hydrating) {
+	if (should_disable_hydration) {
 		set_hydrating(false);
 	}
 	var previous_renderer = current_renderer;
@@ -29,7 +30,7 @@ export function push_renderer(value) {
 
 	return () => {
 		current_renderer = previous_renderer;
-		if (previous_hydrating) {
+		if (should_disable_hydration) {
 			set_hydrating(previous_hydrating);
 		}
 	};

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

@@ -230,7 +230,7 @@ export class Boundary {
 		this.#pending_effect = branch(() => pending(this.#anchor));
 
 		queue_micro_task(() => {
-			var pop_renderer = this.#effect.r !== null ? push_renderer(this.#effect.r) : null;
+			var pop_renderer = push_renderer(this.#effect.r);
 
 			var fragment = (this.#offscreen_fragment = create_fragment());
 			var anchor = create_text();
@@ -324,7 +324,7 @@ export class Boundary {
 		set_active_reaction(this.#effect);
 		set_component_context(this.#effect.ctx);
 
-		var pop_renderer = this.#effect.r !== null ? push_renderer(this.#effect.r) : null;
+		var pop_renderer = push_renderer(this.#effect.r);
 
 		try {
 			Batch.ensure();
@@ -368,7 +368,7 @@ export class Boundary {
 			}
 
 			if (this.#offscreen_fragment) {
-				var pop_renderer = this.#effect.r !== null ? push_renderer(this.#effect.r) : null;
+				var pop_renderer = push_renderer(this.#effect.r);
 				insert_before(this.#anchor, this.#offscreen_fragment);
 				this.#offscreen_fragment = null;
 				pop_renderer?.();

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

@@ -96,7 +96,7 @@ export class BranchManager {
 		// if this batch was made obsolete, bail
 		if (!this.#batches.has(batch)) return;
 
-		var pop_renderer = this.#renderer !== null ? push_renderer(this.#renderer) : null;
+		var pop_renderer = push_renderer(this.#renderer);
 
 		var key = /** @type {Key} */ (this.#batches.get(batch));
 

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

@@ -267,7 +267,7 @@ export function each(node, flags, get_collection, get_key, render_fn, fallback_f
 			return;
 		}
 
-		var pop_renderer = renderer !== null ? push_renderer(renderer) : null;
+		var pop_renderer = push_renderer(renderer);
 
 		state.pending.delete(batch);
 

packages/svelte/src/internal/client/reactivity/effects.js

@@ -513,7 +513,7 @@ export function destroy_block_effect_children(signal) {
 export function destroy_effect(effect, remove_dom = true) {
 	var removed = false;
 
-	var pop_renderer = effect.r !== null ? push_renderer(effect.r) : null;
+	var pop_renderer = push_renderer(effect.r);
 
 	if (
 		(remove_dom || (effect.f & HEAD_EFFECT) !== 0) &&
@@ -738,7 +738,7 @@ export function aborted(effect = /** @type {Effect} */ (active_effect)) {
 export function move_effect(effect, fragment) {
 	if (!effect.nodes) return;
 
-	var pop_renderer = effect.r !== null ? push_renderer(effect.r) : null;
+	var pop_renderer = push_renderer(effect.r);
 
 	/** @type {TemplateNode | null} */
 	var node = effect.nodes.start;

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

@@ -446,7 +446,7 @@ export function update_effect(effect) {
 	active_effect = effect;
 	is_updating_effect = true;
 
-	var pop_renderer = effect.r !== null ? push_renderer(effect.r) : null;
+	var pop_renderer = push_renderer(effect.r);
 
 	if (DEV) {
 		var previous_component_fn = dev_current_component_function;