From 5179221a08ecaa228e56ac660dee252eb34856ec Mon Sep 17 00:00:00 2001
From: Franz Liedke <franz@develophp.org>
Date: Fri, 7 Feb 2020 12:17:11 +0100
Subject: [PATCH] Fix race condition in post preview

The post composer could have been closed in between scheduling and
executing the callback.

Fixes flarum/org#58.
Refs #1881.
---
 framework/core/js/src/forum/components/ReplyPlaceholder.js | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/framework/core/js/src/forum/components/ReplyPlaceholder.js b/framework/core/js/src/forum/components/ReplyPlaceholder.js
index f4f366148..ad2bcc46e 100644
--- a/framework/core/js/src/forum/components/ReplyPlaceholder.js
+++ b/framework/core/js/src/forum/components/ReplyPlaceholder.js
@@ -52,6 +52,10 @@ export default class ReplyPlaceholder extends Component {
     // body with a preview.
     let preview;
     const updateInterval = setInterval(() => {
+      // Since we're polling, the composer may have been closed in the meantime,
+      // so we bail in that case.
+      if (!app.composer.component) return;
+
       const content = app.composer.component.content();
 
       if (preview === content) return;