From 781508dd03298040d9dcdebdff95a03c2e4bc76e Mon Sep 17 00:00:00 2001
From: David Joy <djoy@edx.org>
Date: Mon, 23 Mar 2020 14:15:25 -0400
Subject: [PATCH] =?UTF-8?q?fix:=20Sometimes=20a=20course=20won=E2=80=99t?=
 =?UTF-8?q?=20have=20units.?=
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If a sequence has no unitIds, bail on changing the URL.
---
 src/courseware/CoursewareContainer.jsx | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/src/courseware/CoursewareContainer.jsx b/src/courseware/CoursewareContainer.jsx
index bbe0cb60..4c2fb1b1 100644
--- a/src/courseware/CoursewareContainer.jsx
+++ b/src/courseware/CoursewareContainer.jsx
@@ -97,11 +97,13 @@ function useContentRedirect(courseStatus, sequenceStatus) {
   useEffect(() => {
     if (sequenceStatus === 'loaded' && sequenceId && !unitId) {
       // The position may be null, in which case we'll just assume 0.
-      const unitIndex = sequence.position || 0;
-      const nextUnitId = sequence.unitIds[unitIndex];
-      history.replace(`/course/${courseUsageKey}/${sequence.id}/${nextUnitId}`);
+      if (sequence.unitIds !== undefined && sequence.unitIds.length > 0) {
+        const unitIndex = sequence.position || 0;
+        const nextUnitId = sequence.unitIds[unitIndex];
+        history.replace(`/course/${courseUsageKey}/${sequence.id}/${nextUnitId}`);
+      }
     }
-  }, [sequenceStatus]);
+  }, [sequenceStatus, sequenceId, unitId]);
 }
 
 function useSavedSequencePosition(courseUsageKey, sequenceId, unitId) {