From 0677840feebf200036902bbacfd532fa5ee2054c Mon Sep 17 00:00:00 2001
From: Durran Jordan <durran@gmail.com>
Date: Wed, 17 Aug 2022 11:52:37 -0400
Subject: [PATCH] fix(NODE-4429): check for null topology

---
 src/mongo_client.ts | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/mongo_client.ts b/src/mongo_client.ts
index 8f457cdb5a..d980f3e792 100644
--- a/src/mongo_client.ts
+++ b/src/mongo_client.ts
@@ -501,6 +501,9 @@ export class MongoClient extends TypedEventEmitter<MongoClientEvents> {
 
       Promise.all(activeSessionEnds)
         .then(() => {
+          if (this.topology == null) {
+            return;
+          }
           // If we would attempt to select a server and get nothing back we short circuit
           // to avoid the server selection timeout.
           const selector = readPreferenceServerSelector(ReadPreference.primaryPreferred);