From 1b71926bad4f31718d5d8dcd5971448faaa12697 Mon Sep 17 00:00:00 2001
From: Patrick Kilgore <git@pck.email>
Date: Tue, 15 Jun 2021 13:27:22 -0500
Subject: [PATCH] fix: check observer exists handleIncomingSubscriptionMessage

---
 .../src/realtime-subscription-handshake-link.ts               | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/packages/aws-appsync-subscription-link/src/realtime-subscription-handshake-link.ts b/packages/aws-appsync-subscription-link/src/realtime-subscription-handshake-link.ts
index e8a4348a..bcea0073 100644
--- a/packages/aws-appsync-subscription-link/src/realtime-subscription-handshake-link.ts
+++ b/packages/aws-appsync-subscription-link/src/realtime-subscription-handshake-link.ts
@@ -648,6 +648,10 @@ export class AppSyncRealTimeSubscriptionHandshakeLink extends ApolloLink {
 
     logger({ id, observer, query, variables });
 
+    if (!observer) {
+      return;
+    }
+
     if (type === MESSAGE_TYPES.GQL_DATA && payload && payload.data) {
       if (observer) {
         observer.next(payload);