diff --git a/frontend/src/app/cache.ts b/frontend/src/app/cache.ts
index f862aa9..0f24b00 100644
--- a/frontend/src/app/cache.ts
+++ b/frontend/src/app/cache.ts
@@ -71,7 +71,7 @@ export const selectCourseResult = (courseID: string) => (state: RootState) =>
 export const selectFCEResultsForCourses =
   (courseIDs: string[]) => (state: RootState) =>
     courseIDs.map((courseID) => {
-      if (!state.cache.fces[courseID]) return { courseID, fces: null };
+      if (!state.cache.fces[courseID]) return { courseID, fces: [] };
       return { courseID, fces: state.cache.fces[courseID] };
     });
 
diff --git a/frontend/src/app/fce.ts b/frontend/src/app/fce.ts
index 2f72a2a..b3ae4ae 100644
--- a/frontend/src/app/fce.ts
+++ b/frontend/src/app/fce.ts
@@ -94,8 +94,8 @@ export const aggregateCourses = (
   courses: Course[],
   options: AggregateFCEsOptions
 ) => {
-  const messages = [];
-  const unitsMessage = [];
+  const messages : string[] = [];
+  const unitsMessage : string[] = [];
 
   const coursesWithoutFCEs = data
     .filter(({ fces }) => fces === null)
diff --git a/frontend/src/app/utils.tsx b/frontend/src/app/utils.tsx
index 84bc190..39c5c2d 100644
--- a/frontend/src/app/utils.tsx
+++ b/frontend/src/app/utils.tsx
@@ -68,7 +68,7 @@ export const sessionToShortString = (sessionInfo: Session | FCE | Schedule) => {
 export const compareSessions = (
   session1: Session | FCE,
   session2: Session | FCE
-) => {
+) : number => {
   if (session1.year != session2.year)
     return session1.year < session2.year ? 1 : -1;
 
@@ -88,11 +88,16 @@ export const compareSessions = (
   }
 
   if (session1.session !== session2.session) {
+    if (!session1.session) return 1;
+    if (!session2.session) return -1;
+
     return sessionNumbers.indexOf(session1.session) <
       sessionNumbers.indexOf(session2.session)
       ? 1
       : -1;
   }
+
+  return 0;
 };
 
 export function filterSessions<T extends Session>(sessions: T[]): T[] {
@@ -175,7 +180,7 @@ export function isExactSearch(search: string): boolean {
 }
 
 export function getCourseIDs(search: string): string[] {
-  return search.match(courseIdRegex);
+  return search.match(courseIdRegex) || [];
 }
 
 export function classNames(...classes) {
diff --git a/frontend/src/components/CourseDetail.tsx b/frontend/src/components/CourseDetail.tsx
index f26a69d..e2e900f 100644
--- a/frontend/src/components/CourseDetail.tsx
+++ b/frontend/src/components/CourseDetail.tsx
@@ -20,17 +20,13 @@ const CourseDetail = ({ info, schedules }: Props) => {
     void dispatch(fetchFCEInfosByCourse({ courseIDs: [info.courseID] }));
   }, [dispatch, info.courseID, loggedIn]);
 
-  let sortedSchedules: Schedule[];
-  if (schedules)
-    sortedSchedules = filterSessions([...schedules]).sort(compareSessions);
-
   const fces = useAppSelector((state) => state.cache.fces[info.courseID]);
 
   return (
     <div className="m-auto space-y-4 p-6">
       <CourseCard info={info} showFCEs={false} showCourseInfo={true} />
       {fces && <FCECard fces={fces} />}
-      {schedules && <SchedulesCard scheduleInfos={sortedSchedules} />}
+      {schedules && <SchedulesCard scheduleInfos={filterSessions([...schedules]).sort(compareSessions)} />}
     </div>
   );
 };
diff --git a/frontend/src/components/FCETable.tsx b/frontend/src/components/FCETable.tsx
index 45f386e..3ebee27 100644
--- a/frontend/src/components/FCETable.tsx
+++ b/frontend/src/components/FCETable.tsx
@@ -145,7 +145,7 @@ export const FCETable = ({
   columnVisibility: Record<string, boolean>;
   aggregationOptions: AggregateFCEsOptions;
 }) => {
-  let aggregateData: AggregatedFCEs;
+  let aggregateData: AggregatedFCEs | undefined = undefined;
   let filteredFCEs = fces;
 
   if (fces) {
@@ -160,7 +160,7 @@ export const FCETable = ({
   return (
     <>
       {
-        aggregateData.fcesCounted !== 0 && (
+        aggregateData && aggregateData.fcesCounted !== 0 && (
           <div className="text-md text-gray-700 bg-gray-50 mt-3 rounded p-4">
             <div className="flex items-baseline">
               <h2 className="text-md mb-2">Aggregate Data</h2>
@@ -180,7 +180,7 @@ export const FCETable = ({
               <div className="bg-white flex-1 rounded p-2">
                 <div className="flex content-end">
                   <div className="hidden lg:block">
-                    <StarRating rating={aggregateData.teachingRate} />
+                    <StarRating rating={Number(aggregateData.teachingRate)} />
                   </div>
                   <span className="text-xl lg:ml-2">
                 {aggregateData.teachingRate}
@@ -193,7 +193,7 @@ export const FCETable = ({
               <div className="bg-white flex-1 rounded p-2">
                 <div className="flex content-end">
                   <div className="hidden lg:block">
-                    <StarRating rating={aggregateData.courseRate} />
+                    <StarRating rating={Number(aggregateData.courseRate)} />
                   </div>
                   <span className="text-xl lg:ml-2">
                 {aggregateData.courseRate}
diff --git a/frontend/src/components/ScheduleSearch.tsx b/frontend/src/components/ScheduleSearch.tsx
index 42680dc..b8ad909 100644
--- a/frontend/src/components/ScheduleSearch.tsx
+++ b/frontend/src/components/ScheduleSearch.tsx
@@ -31,7 +31,7 @@ const CourseCombobox = ({
   onSelectedItemsChange: (items: string[]) => void;
 }) => {
   const [inputValue, setInputValue] = useState("");
-  const listRef = useRef();
+  const listRef = useRef(null);
   const dispatch = useAppDispatch();
 
   const allCourses = useAppSelector((state) => state.cache.allCourses);
@@ -70,14 +70,14 @@ const CourseCombobox = ({
     selectedItems,
   } = useMultipleSelection<selectedItem>({
     onSelectedItemsChange: ({ selectedItems }) => {
-      onSelectedItemsChange(selectedItems.map(({ courseID }) => courseID));
+      onSelectedItemsChange(selectedItems?.map(({ courseID }) => courseID) || []);
     },
   });
 
   const filteredCourses = getCourses();
   const rowVirtualizer = useVirtualizer({
     count: filteredCourses.length,
-    getScrollElement: () => listRef.current,
+    getScrollElement: () => listRef.current || null,
     estimateSize: useCallback(() => 40, []),
   });
 
@@ -99,9 +99,9 @@ const CourseCombobox = ({
     selectedItem: null,
     inputValue,
     defaultHighlightedIndex: 0,
-    onInputValueChange: ({ inputValue: newValue }) => setInputValue(newValue),
+    onInputValueChange: ({ inputValue: newValue }) => setInputValue(newValue || ""),
     onHighlightedIndexChange: ({ highlightedIndex }) =>
-      rowVirtualizer.scrollToIndex(highlightedIndex),
+      rowVirtualizer.scrollToIndex(highlightedIndex || 0),
     stateReducer: (state, actionAndChanges) => {
       const { changes, type } = actionAndChanges;
       switch (type) {
@@ -117,7 +117,7 @@ const CourseCombobox = ({
     onStateChange: ({ inputValue, type, selectedItem }) => {
       switch (type) {
         case useCombobox.stateChangeTypes.InputChange:
-          setInputValue(inputValue);
+          setInputValue(inputValue || "");
           break;
         case useCombobox.stateChangeTypes.InputKeyDownEnter:
         case useCombobox.stateChangeTypes.ItemClick:
diff --git a/frontend/src/components/SearchBar.tsx b/frontend/src/components/SearchBar.tsx
index 2177954..f701133 100644
--- a/frontend/src/components/SearchBar.tsx
+++ b/frontend/src/components/SearchBar.tsx
@@ -42,7 +42,7 @@ const AppliedFiltersPill = ({
 
 const AppliedFilters = () => {
   const dispatch = useAppDispatch();
-  const badges = [];
+  const badges : JSX.Element[] = [];
   const filter = useAppSelector((state) => state.filters);
 
   if (filter.departments.active) {
diff --git a/frontend/src/components/Toast.tsx b/frontend/src/components/Toast.tsx
index d9a2a10..ba94bce 100644
--- a/frontend/src/components/Toast.tsx
+++ b/frontend/src/components/Toast.tsx
@@ -9,7 +9,7 @@ type Props = {
 };
 
 export const Toast = (t: ToastType, { message, title, icon }: Props) => {
-  const Icon = icon;
+  const Icon = icon || (() => <div />);
 
   return (
     <div
diff --git a/frontend/src/components/filters/CourseFilter.tsx b/frontend/src/components/filters/CourseFilter.tsx
index 6930afa..814da1a 100644
--- a/frontend/src/components/filters/CourseFilter.tsx
+++ b/frontend/src/components/filters/CourseFilter.tsx
@@ -18,11 +18,11 @@ const CourseFilter = ({ name } : Props) => {
 
   const filteredCourses = useAppSelector((state) => state.user.fceAggregation.filters.courses);
   const fces =  useAppSelector(selectFCEResultsForInstructor(name));
-  const courses = getUnique(fces?.map((fce) => fce.courseID).sort());
+  const courses = getUnique(fces?.map((fce) => fce.courseID).sort() || []);
 
   useEffect(() => {
     dispatch(userSlice.actions.setFilters({ type: "courses",
-      courses: getUnique(fces?.map((fce) => fce.courseID).sort()), instructors: [] }));
+      courses: getUnique(fces?.map((fce) => fce.courseID).sort() || []), instructors: [] }));
   }, [fces, dispatch]);
 
   const setCourses = (courses: string[]) => {
diff --git a/frontend/src/pages/course/[courseID].tsx b/frontend/src/pages/course/[courseID].tsx
index 0c209bd..2eec5cd 100644
--- a/frontend/src/pages/course/[courseID].tsx
+++ b/frontend/src/pages/course/[courseID].tsx
@@ -29,7 +29,7 @@ const CourseDetailPage: NextPage = () => {
   );
 
   if (info) {
-    content = <CourseDetail info={info} schedules={schedules} />;
+    content = <CourseDetail info={info} schedules={schedules || []} />;
   }
 
   return (