From afefd0731b1df939b188272aba029333d0f7685b Mon Sep 17 00:00:00 2001
From: Moonchild <moonchild@palemoon.org>
Date: Thu, 27 Feb 2025 15:13:21 +0100
Subject: [PATCH] No Issue - NULL crash fix in
 nsExternalResourceMap::PendingLoad::OnDataAvailable

Curiously, we should have had this at our fork point (as it was backported
by Mozilla to 52.5.2) by apparently Tobin's import wasn't actually 52.6.0.
:-/
---
 dom/base/nsDocument.cpp | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/dom/base/nsDocument.cpp b/dom/base/nsDocument.cpp
index 26c1025646..09146b2fe2 100644
--- a/dom/base/nsDocument.cpp
+++ b/dom/base/nsDocument.cpp
@@ -995,7 +995,8 @@ nsExternalResourceMap::PendingLoad::OnDataAvailable(nsIRequest* aRequest,
                                                     uint64_t aOffset,
                                                     uint32_t aCount)
 {
-  NS_PRECONDITION(mTargetListener, "Shouldn't be getting called!");
+  // mTargetListener might be null if SetupViewer or AddExternalResource failed.
+  NS_ENSURE_TRUE(mTargetListener, NS_ERROR_FAILURE);
   if (mDisplayDocument->ExternalResourceMap().HaveShutDown()) {
     return NS_BINDING_ABORTED;
   }