fix: set deferreds on initial suspense, too (#17884)

The combination of #17873 and #17805 resulted in a bad merge of the
latter because it wasn't up to date with main. This fixes it. No
changeset because not released yet.

---------

Co-authored-by: Rich Harris <rich.harris@vercel.com>

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

@@ -1,5 +1,6 @@
 /** @import { Derived, Effect, Source } from '#client' */
 /** @import { Batch } from './batch.js'; */
+/** @import { Boundary } from '../dom/blocks/boundary.js'; */
 import { DEV } from 'esm-env';
 import {
 	ERROR_VALUE,
@@ -145,11 +146,13 @@ export function async_derived(fn, label, location) {
 
 		var batch = /** @type {Batch} */ (current_batch);
 
-		// we only increment the batch's pending state for updates, not creation, otherwise
-		// we will decrement to zero before the work that depends on this promise (e.g. a
-		// template effect) has initialized, causing the batch to resolve prematurely
-		if (should_suspend && (effect.f & REACTION_RAN) !== 0) {
-			var decrement_pending = increment_pending();
+		if (should_suspend) {
+			// we only increment the batch's pending state for updates, not creation, otherwise
+			// we will decrement to zero before the work that depends on this promise (e.g. a
+			// template effect) has initialized, causing the batch to resolve prematurely
+			if ((effect.f & REACTION_RAN) !== 0) {
+				var decrement_pending = increment_pending();
+			}
 
 			if (/** @type {Boundary} */ (parent.b).is_rendered()) {
 				deferreds.get(batch)?.reject(STALE_REACTION);