From 3eea77152f4cb4163c5b5502f0ae525eea697c70 Mon Sep 17 00:00:00 2001
From: David Arenas <david.arenas@automattic.com>
Date: Wed, 31 Jul 2024 17:02:37 +0200
Subject: [PATCH] Check if length's PropSignal exists before updating its value

---
 packages/interactivity/src/proxies/state.ts | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/packages/interactivity/src/proxies/state.ts b/packages/interactivity/src/proxies/state.ts
index 7b9c0bf4ea09cf..0978fa2ccd0264 100644
--- a/packages/interactivity/src/proxies/state.ts
+++ b/packages/interactivity/src/proxies/state.ts
@@ -168,7 +168,15 @@ const stateHandlers: ProxyHandler< object > = {
 				objToIterable.get( target )!.value++;
 			}
 
-			if ( Array.isArray( target ) ) {
+			/*
+			 * Modify the `length` property value only if the related
+			 * `PropSignal` exists, which means that there are subscriptions to
+			 * this property.
+			 */
+			if (
+				Array.isArray( target ) &&
+				proxyToProps.get( receiver )?.has( 'length' )
+			) {
 				const length = getPropSignal( receiver, 'length' );
 				length.setValue( target.length );
 			}