[Lint] Fix lint errors

services/backend/src/routes/courses.ts

@@ -43,7 +43,7 @@ router.get<never, CanError<CourseYearlyStatsResBody>, CourseYearlyStatsReqBody,
   async (req, res) => {
     const { courses, substitutions, separate, fromYearCode, toYearCode } = req.query
 
-    if (!courses || !courses.length) {
+    if (!courses?.length) {
       return res.status(422).send({ error: 'Missing required query parameters' })
     }
 

services/frontend/src/components/common/EquivalenceGroupChip.tsx

@@ -37,7 +37,7 @@ const CourseCodes = ({
 }) => (
   <Stack direction="row" divider={<span>{separator}</span>} spacing={0.5}>
     {courses.map(course => (
-      <CourseCode code={course.code} getTextIn={getTextIn} key={course.code} name={course.name} />
+      <CourseCode code={course?.code} getTextIn={getTextIn} key={course?.code} name={course?.name} />
     ))}
   </Stack>
 )