From 05b0798824aa9686b8a878ee9ccf691b04d57108 Mon Sep 17 00:00:00 2001
From: Jonas Jenwald <jonas.jenwald@gmail.com>
Date: Sat, 10 Apr 2021 12:46:45 +0200
Subject: [PATCH] Check that the correct `pdfDocument` is still active, before
 rendering the outline/attachments/layers

*This patch fixes some technical debt in the viewer.*

Given that most API methods are (purposely) asynchronous, there's always a risk that the viewer could have been `close`d before the requested data arrives.
Lately we've started to check this case before using the data, to prevent errors and/or inconsistent state, however the outline/attachments/layers fetching and rendering is old enough that it pre-dates those checks.
---
 web/app.js | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/web/app.js b/web/app.js
index 27dc2935f..7bc296bd4 100644
--- a/web/app.js
+++ b/web/app.js
@@ -1383,14 +1383,23 @@ const PDFViewerApplication = {
 
     onePageRendered.then(() => {
       pdfDocument.getOutline().then(outline => {
+        if (pdfDocument !== this.pdfDocument) {
+          return; // The document was closed while the outline resolved.
+        }
         this.pdfOutlineViewer.render({ outline, pdfDocument });
       });
       pdfDocument.getAttachments().then(attachments => {
+        if (pdfDocument !== this.pdfDocument) {
+          return; // The document was closed while the attachments resolved.
+        }
         this.pdfAttachmentViewer.render({ attachments });
       });
       // Ensure that the layers accurately reflects the current state in the
       // viewer itself, rather than the default state provided by the API.
       pdfViewer.optionalContentConfigPromise.then(optionalContentConfig => {
+        if (pdfDocument !== this.pdfDocument) {
+          return; // The document was closed while the layers resolved.
+        }
         this.pdfLayerViewer.render({ optionalContentConfig, pdfDocument });
       });
       if (