fix: [AA-1018] api cleanup

Fix error when moving from courseHome to courseware.

src/courseware/course/sequence/sequence-navigation/UnitNavigationEffortEstimate.jsx

@@ -24,7 +24,7 @@ function UnitNavigationEffortEstimate({
   const sequence = useModel('sequences', sequenceId);
   const nextSequence = useModel('sequences', nextSequenceId);
 
-  if (!sequence || !nextSequence) {
+  if (!sequence || Object.keys(sequence).length === 0 || !nextSequence || Object.keys(nextSequence).length === 0) {
     return children;
   }
 

src/generic/model-store/hooks.js

@@ -1,8 +1,11 @@
 import { useSelector, shallowEqual } from 'react-redux';
 
+/*
+  Return the selected model with the given id, or an empty object if the model does not exist "{}".
+ */
 export function useModel(type, id) {
   return useSelector(
-    state => (state.models[type] !== undefined ? state.models[type][id] : {}),
+    state => ((state.models[type] !== undefined && state.models[type][id] !== undefined) ? state.models[type][id] : {}),
     shallowEqual,
   );
 }
@@ -10,7 +13,7 @@ export function useModel(type, id) {
 export function useModels(type, ids) {
   return useSelector(
     state => ids.map(
-      id => (state.models[type] !== undefined ? state.models[type][id] : {}),
+      id => ((state.models[type] !== undefined && state.models[type][id] !== undefined) ? state.models[type][id] : {}),
     ),
     shallowEqual,
   );

src/tab-page/TabContainer.jsx

@@ -10,6 +10,7 @@ export default function TabContainer(props) {
   const {
     children,
     fetch,
+    slice,
     tab,
   } = props;
 
@@ -25,14 +26,14 @@ export default function TabContainer(props) {
   const {
     courseId,
     courseStatus,
-  } = useSelector(state => state.courseHome);
+  } = useSelector(state => state[slice]);
 
   return (
     <TabPage
       activeTabSlug={tab}
       courseId={courseId}
       courseStatus={courseStatus}
-      metadataModel="courseHomeMeta"
+      metadataModel={`${slice}Meta`}
     >
       {courseId && <OuterExamTimer courseId={courseId} />}
       {children}
@@ -43,5 +44,6 @@ export default function TabContainer(props) {
 TabContainer.propTypes = {
   children: PropTypes.node.isRequired,
   fetch: PropTypes.func.isRequired,
+  slice: PropTypes.string.isRequired,
   tab: PropTypes.string.isRequired,
 };

src/tab-page/TabContainer.test.jsx

@@ -22,6 +22,7 @@ describe('Tab Container', () => {
     mockData = {
       fetch: mockFetch,
       tab: 'dummy',
+      slice: 'courseware',
     };
     const store = await initializeTestStore({ excludeFetchSequence: true });
     courseId = store.getState().courseware.courseId;
@@ -57,6 +58,7 @@ describe('Tab Container', () => {
           <TabContainer
             fetch={() => mockFetch(match.params.courseId, match.params.targetUserId)}
             tab="dummy"
+            slice="courseHome"
           >
             children={[]}
           </TabContainer>