From 49614cfbb772772098d104f8864d8107e24e48e7 Mon Sep 17 00:00:00 2001
From: "w.dawiskiba" <w.dawiskiba@nomtek.com>
Date: Thu, 1 Dec 2022 15:57:06 +0100
Subject: [PATCH] added null check to prevent NullPointerExceptions

---
 lib/src/main/java/io/ably/lib/realtime/Presence.java | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/lib/src/main/java/io/ably/lib/realtime/Presence.java b/lib/src/main/java/io/ably/lib/realtime/Presence.java
index 84bc1acac..1e835369d 100644
--- a/lib/src/main/java/io/ably/lib/realtime/Presence.java
+++ b/lib/src/main/java/io/ably/lib/realtime/Presence.java
@@ -1176,9 +1176,13 @@ synchronized List<PresenceMessage> endSync() {
                 /* any members that were present at the start of the sync,
                  * and have not been seen in sync, can be removed */
                 for(String itemKey: residualMembers) {
-                    /* clone presence message as it still can be in the internal presence map */
-                    removedEntries.add((PresenceMessage)members.get(itemKey).clone());
-                    members.remove(itemKey);
+                    PresenceMessage removedMember = members.remove(itemKey);
+                    /* This null check is added as a potential fix for an issue that
+                     * could not be reproduced, reported here https://github.com/ably/ably-java/issues/853 */
+                    if(removedMember != null) {
+                        /* clone presence message as it still can be in the internal presence map */
+                        removedEntries.add((PresenceMessage) removedMember.clone());
+                    }
                 }
                 residualMembers = null;