[CourseStats] Add better handling for invalid values

services/backend/src/routes/courses.ts

@@ -60,7 +60,7 @@ router.get<never, CanError<CourseYearlyStatsResBody>, CourseYearlyStatsReqBody,
 
     const courseCodes = handleQueryArrays(codes)
 
-    if (!courseCodes) {
+    if (!courseCodes?.length) {
       return res.status(422).send({ error: 'Missing required query parameters' })
     }
 

services/backend/src/services/courses/creditsAndEnrollmentsOfCourse.ts

@@ -88,7 +88,6 @@ export const getCreditsForCourses = async (codeGroups: string[][], unification:
     }
   }
 
-  // return completedGroups
   return completedGroups.filter(group => group.length)
 }
 

services/backend/src/services/courses/index.ts

@@ -4,6 +4,7 @@ import { Op, fn as dbFn, col as dbCol } from 'sequelize'
 import { Credit, Enrollment } from '@oodikone/shared/models'
 import { Name, EnrollmentState, Unification } from '@oodikone/shared/types'
 import { dateIsBetween } from '@oodikone/shared/util/datetime'
+import logger from '../../../src/util/logger'
 import { CourseModel, CreditModel, EnrollmentModel, OrganizationModel, SISStudyRightElementModel } from '../../models'
 import { isOpenUniCourseCode } from '../../util'
 import { CourseYearlyStatsCounter } from './courseYearlyStatsCounter'
@@ -333,7 +334,8 @@ export const getCourseYearlyStats = async (
         })
 
       if (!course) {
-        return null
+        logger.error('Course for course stats not found with code' + courseCode)
+        return {}
       }
 
       const [openStats, regularStats, unifyStats] = await Promise.all([