From 9ab904fd198c7471a55cff6799c0bbc13e063df6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?R=C3=A9gis=20Behmo?= <regis@behmo.com>
Date: Tue, 9 Nov 2021 17:12:24 +0100
Subject: [PATCH] fix: "Uncaught TypeError: n is null" during login to LMS
 (#29192)

When signing in from the LMS, the authentication request succeeds but
the user was never redirected to the dashboard. This is because of a
js error:

    Uncaught TypeError: userCookie is null
        userFromEdxUserCookie
        http://maple.openedx.overhang.io:8000/static/js/student_account/utils.js:32

The error comes from the fact that the util.js code ignores the
EDXAPP_EDXMKTG_USER_INFO_COOKIE_NAME setting name. Instead the cookie
name is abritrarily prefixed by "stage-" or "prod-" depending on the
hostname. This seems to be primarily motivated by the definition of
edX.org staging/prod environment hostnames :-(

To resolve this issue, we decided that the actual cookie name was not so
important. Instead, the js code needs to not crash even when the cookie
is absent.

This issue was first reported here:
https://github.com/edx/edx-platform/pull/28170#issuecomment-890449885

Close https://github.com/openedx/build-test-release-wg/issues/104
---
 lms/static/js/spec/student_account/utils_spec.js | 14 ++++++++++++++
 lms/static/js/student_account/utils.js           |  4 ++++
 2 files changed, 18 insertions(+)

diff --git a/lms/static/js/spec/student_account/utils_spec.js b/lms/static/js/spec/student_account/utils_spec.js
index 445ddae7f1..03ecbe6fb9 100644
--- a/lms/static/js/spec/student_account/utils_spec.js
+++ b/lms/static/js/spec/student_account/utils_spec.js
@@ -21,5 +21,19 @@ define(['jquery', 'js/student_account/utils'],
                 expect(user).toEqual(userInfo);
             });
         });
+
+        describe('userFromEdxUserCookie', function() {
+            var user;
+
+            beforeEach(function() {
+                $.cookie('edx-user-info', null);
+            });
+
+            it('returns empty user information when cookie is absent', function() {
+                spyOn($, 'cookie').and.returnValue(null);
+                user = Utils.userFromEdxUserCookie();
+                expect(user).toEqual({});
+            });
+        });
     }
 );
diff --git a/lms/static/js/student_account/utils.js b/lms/static/js/student_account/utils.js
index fb539b658c..bdb8ee8361 100644
--- a/lms/static/js/student_account/utils.js
+++ b/lms/static/js/student_account/utils.js
@@ -27,6 +27,10 @@
                 cookie = document.cookie.match('(^|;)\\s*' + edxUserCookie + '\\s*=\\s*([^;]+)');
                 userCookie = cookie ? cookie.pop() : $.cookie(edxUserCookie);
 
+                if (!userCookie) {
+                    return {};
+                }
+
                 // returns the user object from cookie. Replaces '054' with ',' and removes '\'
                 user = userCookie.replace(/\\/g, '').replace(/054/g, ',');
                 user = user.substring(1, user.length - 1);