From f2c864ec667fc5f85e5ecb2e6379262e0dff093b Mon Sep 17 00:00:00 2001
From: Ben Newman <ben@meteor.com>
Date: Tue, 31 Jul 2018 22:38:18 -0400
Subject: [PATCH] Avoid TDZ error from calling observe callbacks synchronously.

Should fix #10092.
---
 packages/autoupdate/autoupdate_client.js | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/packages/autoupdate/autoupdate_client.js b/packages/autoupdate/autoupdate_client.js
index db9075d39f..a3ce4d2449 100644
--- a/packages/autoupdate/autoupdate_client.js
+++ b/packages/autoupdate/autoupdate_client.js
@@ -96,9 +96,17 @@ Autoupdate._retrySubscription = () => {
     },
 
     onReady() {
+      // Call checkNewVersionDocument with a slight delay, so that the
+      // const handle declaration is guaranteed to be initialized, even if
+      // the added or changed callbacks are called synchronously.
+      const resolved = Promise.resolve();
+      function check(doc) {
+        resolved.then(() => checkNewVersionDocument(doc));
+      }
+
       const handle = ClientVersions.find().observe({
-        added: checkNewVersionDocument,
-        changed: checkNewVersionDocument
+        added: check,
+        changed: check
       });
 
       function checkNewVersionDocument(doc) {