From b26d736809a49941fe2a9fc7b691365496f20eeb Mon Sep 17 00:00:00 2001
From: Jonas Jenwald <jonas.jenwald@gmail.com>
Date: Thu, 13 Aug 2020 13:17:30 +0200
Subject: [PATCH] Ensure that the "DocException" message handler, in the API,
 will always either error or warn (depending on the build) if a valid `Error`
 isn't found

Having this present would have made debugging issues 11941 and 12209 so much quicker and easier.
---
 src/display/api.js | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/src/display/api.js b/src/display/api.js
index c94bf977f..ff17ffec8 100644
--- a/src/display/api.js
+++ b/src/display/api.js
@@ -2271,11 +2271,16 @@ class WorkerTransport {
           reason = new UnknownErrorException(ex.message, ex.details);
           break;
       }
-      if (
-        typeof PDFJSDev === "undefined" ||
-        PDFJSDev.test("!PRODUCTION || TESTING")
-      ) {
-        assert(reason instanceof Error, "DocException: expected an Error.");
+      if (!(reason instanceof Error)) {
+        const msg = "DocException - expected a valid Error.";
+        if (
+          typeof PDFJSDev === "undefined" ||
+          PDFJSDev.test("!PRODUCTION || TESTING")
+        ) {
+          unreachable(msg);
+        } else {
+          warn(msg);
+        }
       }
       loadingTask._capability.reject(reason);
     });