diff --git a/backend/src/data/dwengo-entity-repository.ts b/backend/src/data/dwengo-entity-repository.ts
index 368f3a2c..e29d9ede 100644
--- a/backend/src/data/dwengo-entity-repository.ts
+++ b/backend/src/data/dwengo-entity-repository.ts
@@ -4,13 +4,13 @@ export abstract class DwengoEntityRepository<
     T extends object,
 > extends EntityRepository<T> {
     public async save(entity: T) {
-        let em = this.getEntityManager();
+        const em = this.getEntityManager();
         em.persist(entity);
         await em.flush();
     }
     public async deleteWhere(query: FilterQuery<T>) {
-        let toDelete = await this.findOne(query);
-        let em = this.getEntityManager();
+        const toDelete = await this.findOne(query);
+        const em = this.getEntityManager();
         if (toDelete) {
             em.remove(toDelete);
             await em.flush();
diff --git a/backend/src/data/questions/answer-repository.ts b/backend/src/data/questions/answer-repository.ts
index 6a2629f4..6c45211c 100644
--- a/backend/src/data/questions/answer-repository.ts
+++ b/backend/src/data/questions/answer-repository.ts
@@ -9,7 +9,7 @@ export class AnswerRepository extends DwengoEntityRepository<Answer> {
         author: Teacher;
         content: string;
     }): Promise<Answer> {
-        let answerEntity = new Answer();
+        const answerEntity = new Answer();
         answerEntity.toQuestion = answer.toQuestion;
         answerEntity.author = answer.author;
         answerEntity.content = answer.content;
diff --git a/backend/src/data/questions/question-repository.ts b/backend/src/data/questions/question-repository.ts
index 517305f1..8852a9ba 100644
--- a/backend/src/data/questions/question-repository.ts
+++ b/backend/src/data/questions/question-repository.ts
@@ -9,7 +9,7 @@ export class QuestionRepository extends DwengoEntityRepository<Question> {
         author: Student;
         content: string;
     }): Promise<Question> {
-        let questionEntity = new Question();
+        const questionEntity = new Question();
         questionEntity.learningObjectHruid = question.loId.hruid;
         questionEntity.learningObjectLanguage = question.loId.language;
         questionEntity.learningObjectVersion = question.loId.version;
diff --git a/backend/src/entities/assignments/assignment.entity.ts b/backend/src/entities/assignments/assignment.entity.ts
index e883632b..7909b107 100644
--- a/backend/src/entities/assignments/assignment.entity.ts
+++ b/backend/src/entities/assignments/assignment.entity.ts
@@ -12,7 +12,7 @@ import { Language } from '../content/language.js';
 
 @Entity()
 export class Assignment {
-    @ManyToOne({ entity: () => Class, primary: true })
+    @ManyToOne({ entity: () => {return Class}, primary: true })
     within!: Class;
 
     @PrimaryKey({ type: 'number' })
@@ -27,9 +27,9 @@ export class Assignment {
     @Property({ type: 'string' })
     learningPathHruid!: string;
 
-    @Enum({ items: () => Language })
+    @Enum({ items: () => {return Language} })
     learningPathLanguage!: Language;
 
-    @OneToMany({ entity: () => Group, mappedBy: 'assignment' })
+    @OneToMany({ entity: () => {return Group}, mappedBy: 'assignment' })
     groups!: Group[];
 }
diff --git a/backend/src/entities/assignments/group.entity.ts b/backend/src/entities/assignments/group.entity.ts
index 80da7d8b..a68eb5a0 100644
--- a/backend/src/entities/assignments/group.entity.ts
+++ b/backend/src/entities/assignments/group.entity.ts
@@ -4,12 +4,12 @@ import { Student } from '../users/student.entity.js';
 
 @Entity()
 export class Group {
-    @ManyToOne({ entity: () => Assignment, primary: true })
+    @ManyToOne({ entity: () => {return Assignment}, primary: true })
     assignment!: Assignment;
 
     @PrimaryKey({ type: 'integer' })
     groupNumber!: number;
 
-    @ManyToMany({ entity: () => Student })
+    @ManyToMany({ entity: () => {return Student} })
     members!: Student[];
 }
diff --git a/backend/src/entities/assignments/submission.entity.ts b/backend/src/entities/assignments/submission.entity.ts
index 02cbeeae..bd0936a1 100644
--- a/backend/src/entities/assignments/submission.entity.ts
+++ b/backend/src/entities/assignments/submission.entity.ts
@@ -8,7 +8,7 @@ export class Submission {
     @PrimaryKey({ type: 'string' })
     learningObjectHruid!: string;
 
-    @Enum({ items: () => Language, primary: true })
+    @Enum({ items: () => {return Language}, primary: true })
     learningObjectLanguage!: Language;
 
     @PrimaryKey({ type: 'string' })
@@ -17,13 +17,13 @@ export class Submission {
     @PrimaryKey({ type: 'integer' })
     submissionNumber!: number;
 
-    @ManyToOne({ entity: () => Student })
+    @ManyToOne({ entity: () => {return Student} })
     submitter!: Student;
 
     @Property({ type: 'datetime' })
     submissionTime!: Date;
 
-    @ManyToOne({ entity: () => Group, nullable: true })
+    @ManyToOne({ entity: () => {return Group}, nullable: true })
     onBehalfOf?: Group;
 
     @Property({ type: 'json' })
diff --git a/backend/src/entities/classes/class-join-request.entity.ts b/backend/src/entities/classes/class-join-request.entity.ts
index 00cb5185..8e88999c 100644
--- a/backend/src/entities/classes/class-join-request.entity.ts
+++ b/backend/src/entities/classes/class-join-request.entity.ts
@@ -4,13 +4,13 @@ import { Class } from './class.entity';
 
 @Entity()
 export class ClassJoinRequest {
-    @ManyToOne({ entity: () => Student, primary: true })
+    @ManyToOne({ entity: () => {return Student}, primary: true })
     requester!: Student;
 
-    @ManyToOne({ entity: () => Class, primary: true })
+    @ManyToOne({ entity: () => {return Class}, primary: true })
     class!: Class;
 
-    @Enum(() => ClassJoinRequestStatus)
+    @Enum(() => {return ClassJoinRequestStatus})
     status!: ClassJoinRequestStatus;
 }
 
diff --git a/backend/src/entities/classes/class.entity.ts b/backend/src/entities/classes/class.entity.ts
index 1f5835d2..2ad98c84 100644
--- a/backend/src/entities/classes/class.entity.ts
+++ b/backend/src/entities/classes/class.entity.ts
@@ -17,9 +17,9 @@ export class Class {
     @Property({ type: 'string' })
     displayName!: string;
 
-    @ManyToMany(() => Teacher)
+    @ManyToMany(() => {return Teacher})
     teachers!: Collection<Teacher>;
 
-    @ManyToMany(() => Student)
+    @ManyToMany(() => {return Student})
     students!: Collection<Student>;
 }
diff --git a/backend/src/entities/classes/teacher-invitation.entity.ts b/backend/src/entities/classes/teacher-invitation.entity.ts
index 375bf719..feba8fc3 100644
--- a/backend/src/entities/classes/teacher-invitation.entity.ts
+++ b/backend/src/entities/classes/teacher-invitation.entity.ts
@@ -7,12 +7,12 @@ import { Class } from './class.entity.js';
  */
 @Entity()
 export class TeacherInvitation {
-    @ManyToOne({ entity: () => Teacher, primary: true })
+    @ManyToOne({ entity: () => {return Teacher}, primary: true })
     sender!: Teacher;
 
-    @ManyToOne({ entity: () => Teacher, primary: true })
+    @ManyToOne({ entity: () => {return Teacher}, primary: true })
     receiver!: Teacher;
 
-    @ManyToOne({ entity: () => Class, primary: true })
+    @ManyToOne({ entity: () => {return Class}, primary: true })
     class!: Class;
 }
diff --git a/backend/src/entities/content/attachment.entity.ts b/backend/src/entities/content/attachment.entity.ts
index 5a77d4b7..2ead7262 100644
--- a/backend/src/entities/content/attachment.entity.ts
+++ b/backend/src/entities/content/attachment.entity.ts
@@ -3,7 +3,7 @@ import { LearningObject } from './learning-object.entity.js';
 
 @Entity()
 export class Attachment {
-    @ManyToOne({ entity: () => LearningObject, primary: true })
+    @ManyToOne({ entity: () => {return LearningObject}, primary: true })
     learningObject!: LearningObject;
 
     @PrimaryKey({ type: 'integer' })
diff --git a/backend/src/entities/content/learning-object.entity.ts b/backend/src/entities/content/learning-object.entity.ts
index aeee268d..c5bfe08f 100644
--- a/backend/src/entities/content/learning-object.entity.ts
+++ b/backend/src/entities/content/learning-object.entity.ts
@@ -17,13 +17,13 @@ export class LearningObject {
     @PrimaryKey({ type: 'string' })
     hruid!: string;
 
-    @Enum({ items: () => Language, primary: true })
+    @Enum({ items: () => {return Language}, primary: true })
     language!: Language;
 
     @PrimaryKey({ type: 'string' })
     version: string = '1';
 
-    @ManyToMany({ entity: () => Teacher })
+    @ManyToMany({ entity: () => {return Teacher} })
     admins!: Teacher[];
 
     @Property({ type: 'string' })
@@ -47,7 +47,7 @@ export class LearningObject {
     @Property({ type: 'array' })
     skosConcepts!: string[];
 
-    @Embedded({ entity: () => EducationalGoal, array: true })
+    @Embedded({ entity: () => {return EducationalGoal}, array: true })
     educationalGoals: EducationalGoal[] = [];
 
     @Property({ type: 'string' })
@@ -62,7 +62,7 @@ export class LearningObject {
     @Property({ type: 'integer' })
     estimatedTime!: number;
 
-    @Embedded({ entity: () => ReturnValue })
+    @Embedded({ entity: () => {return ReturnValue} })
     returnValue!: ReturnValue;
 
     @Property({ type: 'bool' })
@@ -71,7 +71,7 @@ export class LearningObject {
     @Property({ type: 'string', nullable: true })
     contentLocation?: string;
 
-    @OneToMany({ entity: () => Attachment, mappedBy: 'learningObject' })
+    @OneToMany({ entity: () => {return Attachment}, mappedBy: 'learningObject' })
     attachments: Attachment[] = [];
 
     @Property({ type: 'blob' })
diff --git a/backend/src/entities/content/learning-path.entity.ts b/backend/src/entities/content/learning-path.entity.ts
index f426cdfe..f758dace 100644
--- a/backend/src/entities/content/learning-path.entity.ts
+++ b/backend/src/entities/content/learning-path.entity.ts
@@ -16,10 +16,10 @@ export class LearningPath {
     @PrimaryKey({ type: 'string' })
     hruid!: string;
 
-    @Enum({ items: () => Language, primary: true })
+    @Enum({ items: () => {return Language}, primary: true })
     language!: Language;
 
-    @ManyToMany({ entity: () => Teacher })
+    @ManyToMany({ entity: () => {return Teacher} })
     admins!: Teacher[];
 
     @Property({ type: 'string' })
@@ -31,7 +31,7 @@ export class LearningPath {
     @Property({ type: 'blob' })
     image!: string;
 
-    @Embedded({ entity: () => LearningPathNode, array: true })
+    @Embedded({ entity: () => {return LearningPathNode}, array: true })
     nodes: LearningPathNode[] = [];
 }
 
@@ -40,7 +40,7 @@ export class LearningPathNode {
     @Property({ type: 'string' })
     learningObjectHruid!: string;
 
-    @Enum({ items: () => Language })
+    @Enum({ items: () => {return Language} })
     language!: Language;
 
     @Property({ type: 'string' })
@@ -52,7 +52,7 @@ export class LearningPathNode {
     @Property({ type: 'bool' })
     startNode!: boolean;
 
-    @Embedded({ entity: () => LearningPathTransition, array: true })
+    @Embedded({ entity: () => {return LearningPathTransition}, array: true })
     transitions!: LearningPathTransition[];
 }
 
@@ -61,6 +61,6 @@ export class LearningPathTransition {
     @Property({ type: 'string' })
     condition!: string;
 
-    @OneToOne({ entity: () => LearningPathNode })
+    @OneToOne({ entity: () => {return LearningPathNode} })
     next!: LearningPathNode;
 }
diff --git a/backend/src/entities/questions/answer.entity.ts b/backend/src/entities/questions/answer.entity.ts
index b15dce71..2690d50d 100644
--- a/backend/src/entities/questions/answer.entity.ts
+++ b/backend/src/entities/questions/answer.entity.ts
@@ -4,10 +4,10 @@ import { Teacher } from '../users/teacher.entity';
 
 @Entity()
 export class Answer {
-    @ManyToOne({ entity: () => Teacher, primary: true })
+    @ManyToOne({ entity: () => {return Teacher}, primary: true })
     author!: Teacher;
 
-    @ManyToOne({ entity: () => Question, primary: true })
+    @ManyToOne({ entity: () => {return Question}, primary: true })
     toQuestion!: Question;
 
     @PrimaryKey({ type: 'integer' })
diff --git a/backend/src/entities/questions/question.entity.ts b/backend/src/entities/questions/question.entity.ts
index 6c0d07e5..5830c816 100644
--- a/backend/src/entities/questions/question.entity.ts
+++ b/backend/src/entities/questions/question.entity.ts
@@ -7,7 +7,7 @@ export class Question {
     @PrimaryKey({ type: 'string' })
     learningObjectHruid!: string;
 
-    @Enum({ items: () => Language, primary: true })
+    @Enum({ items: () => {return Language}, primary: true })
     learningObjectLanguage!: Language;
 
     @PrimaryKey({ type: 'string' })
@@ -16,7 +16,7 @@ export class Question {
     @PrimaryKey({ type: 'integer' })
     sequenceNumber!: number;
 
-    @ManyToOne({ entity: () => Student })
+    @ManyToOne({ entity: () => {return Student} })
     author!: Student;
 
     @Property({ type: 'datetime' })
diff --git a/backend/src/entities/users/student.entity.ts b/backend/src/entities/users/student.entity.ts
index dc791adc..ccfa7dfc 100644
--- a/backend/src/entities/users/student.entity.ts
+++ b/backend/src/entities/users/student.entity.ts
@@ -4,12 +4,12 @@ import { Class } from '../classes/class.entity.js';
 import { Group } from '../assignments/group.entity.js';
 import { StudentRepository } from '../../data/users/student-repository.js';
 
-@Entity({ repository: () => StudentRepository })
+@Entity({ repository: () => {return StudentRepository} })
 export class Student extends User {
-    @ManyToMany(() => Class)
+    @ManyToMany(() => {return Class})
     classes!: Collection<Class>;
 
-    @ManyToMany(() => Group)
+    @ManyToMany(() => {return Group})
     groups!: Collection<Group>;
 
     constructor(
diff --git a/backend/src/entities/users/teacher.entity.ts b/backend/src/entities/users/teacher.entity.ts
index 2327527c..eaaa8327 100644
--- a/backend/src/entities/users/teacher.entity.ts
+++ b/backend/src/entities/users/teacher.entity.ts
@@ -4,6 +4,6 @@ import { Class } from '../classes/class.entity.js';
 
 @Entity()
 export class Teacher extends User {
-    @ManyToMany(() => Class)
+    @ManyToMany(() => {return Class})
     classes!: Collection<Class>;
 }
diff --git a/backend/src/mikro-orm.config.ts b/backend/src/mikro-orm.config.ts
index da118827..88996cf9 100644
--- a/backend/src/mikro-orm.config.ts
+++ b/backend/src/mikro-orm.config.ts
@@ -15,9 +15,9 @@ function config(testingMode: boolean = false): Options {
 
             // Workaround: vitest: `TypeError: Unknown file extension ".ts"` (ERR_UNKNOWN_FILE_EXTENSION)
             // (see https://mikro-orm.io/docs/guide/project-setup#testing-the-endpoint)
-            dynamicImportProvider: (id) => import(id),
+            dynamicImportProvider: (id) => {return import(id)},
         };
-    } else {
+    } 
         return {
             driver: PostgreSqlDriver,
             host: getEnvVar(EnvVars.DbHost),
@@ -29,7 +29,7 @@ function config(testingMode: boolean = false): Options {
             entitiesTs: entitiesTs,
             debug: true,
         };
-    }
+    
 }
 
 export default config;
diff --git a/backend/src/routes/assignment.ts b/backend/src/routes/assignment.ts
index fcb6e9da..eb49144f 100644
--- a/backend/src/routes/assignment.ts
+++ b/backend/src/routes/assignment.ts
@@ -1,7 +1,7 @@
 import express from 'express'
 const router = express.Router();
 
-// root endpoint used to search objects
+// Root endpoint used to search objects
 router.get('/', (req, res) => {
     res.json({
         assignments: [
@@ -11,7 +11,7 @@ router.get('/', (req, res) => {
     });
 });
 
-// information about an assignment with id 'id'
+// Information about an assignment with id 'id'
 router.get('/:id', (req, res) => {
     res.json({
         id: req.params.id,
diff --git a/backend/src/routes/class.ts b/backend/src/routes/class.ts
index e554a7f2..fa7a2310 100644
--- a/backend/src/routes/class.ts
+++ b/backend/src/routes/class.ts
@@ -1,7 +1,7 @@
 import express from 'express'
 const router = express.Router();
 
-// root endpoint used to search objects
+// Root endpoint used to search objects
 router.get('/', (req, res) => {
     res.json({
         classes: [
@@ -11,7 +11,7 @@ router.get('/', (req, res) => {
     });
 });
 
-// information about an class with id 'id'
+// Information about an class with id 'id'
 router.get('/:id', (req, res) => {
     res.json({
         id: req.params.id,
diff --git a/backend/src/routes/group.ts b/backend/src/routes/group.ts
index e55dddd1..e951a8a7 100644
--- a/backend/src/routes/group.ts
+++ b/backend/src/routes/group.ts
@@ -1,7 +1,7 @@
 import express from 'express'
 const router = express.Router();
 
-// root endpoint used to search objects
+// Root endpoint used to search objects
 router.get('/', (req, res) => {
     res.json({
         groups: [
@@ -11,20 +11,20 @@ router.get('/', (req, res) => {
     });
 });
 
-// information about a group (members, ... [TODO DOC])
+// Information about a group (members, ... [TODO DOC])
 router.get('/:id', (req, res) => {
     res.json({
         id: req.params.id,
         assignment: '0',
         students: [ '0' ],
         submissions: [ '0' ],
-        // reference to other endpoint
-        // should be less hardcoded
+        // Reference to other endpoint
+        // Should be less hardcoded
         questions: `/group/${req.params.id}/question`, 
     });
 })
 
-// the list of questions a group has made
+// The list of questions a group has made
 router.get('/:id/question', (req, res) => {
     res.json({
         questions: [ '0' ],
diff --git a/backend/src/routes/login.ts b/backend/src/routes/login.ts
index 550e6d93..bc2ed3d8 100644
--- a/backend/src/routes/login.ts
+++ b/backend/src/routes/login.ts
@@ -1,11 +1,11 @@
 import express from 'express'
 const router = express.Router();
 
-// returns login paths for IDP
+// Returns login paths for IDP
 router.get('/', (req, res) => {
     res.json({
-        // dummy variables, needs to be changed
-        // with IDP endpoints
+        // Dummy variables, needs to be changed
+        // With IDP endpoints
         leerkracht: '/login-leerkracht',
         leerling: '/login-leerling',
     });
diff --git a/backend/src/routes/question.ts b/backend/src/routes/question.ts
index 25d168b7..040f742d 100644
--- a/backend/src/routes/question.ts
+++ b/backend/src/routes/question.ts
@@ -1,7 +1,7 @@
 import express from 'express'
 const router = express.Router();
 
-// root endpoint used to search objects
+// Root endpoint used to search objects
 router.get('/', (req, res) => {
     res.json({
         questions: [
@@ -11,7 +11,7 @@ router.get('/', (req, res) => {
     });
 });
 
-// information about an question with id 'id'
+// Information about an question with id 'id'
 router.get('/:id', (req, res) => {
     res.json({
         id: req.params.id,
diff --git a/backend/src/routes/student.ts b/backend/src/routes/student.ts
index a11c1fbc..bc3f588b 100644
--- a/backend/src/routes/student.ts
+++ b/backend/src/routes/student.ts
@@ -1,7 +1,7 @@
 import express from 'express'
 const router = express.Router();
 
-// root endpoint used to search objects
+// Root endpoint used to search objects
 router.get('/', (req, res) => {
     res.json({
         students: [
@@ -11,7 +11,7 @@ router.get('/', (req, res) => {
     });
 });
 
-// information about a student's profile
+// Information about a student's profile
 router.get('/:id', (req, res) => {
     res.json({
         id: req.params.id,
@@ -27,14 +27,14 @@ router.get('/:id', (req, res) => {
     });
 });
 
-// the list of classes a student is in
+// The list of classes a student is in
 router.get('/:id/classes', (req, res) => {
     res.json({
         classes: [ '0' ],
     });
 })
 
-// the list of submissions a student has made
+// The list of submissions a student has made
 router.get('/:id/submissions', (req, res) => {
     res.json({
         submissions: [ '0' ],
@@ -42,14 +42,14 @@ router.get('/:id/submissions', (req, res) => {
 })
 
   
-// the list of assignments a student has
+// The list of assignments a student has
 router.get('/:id/assignments', (req, res) => {
     res.json({
         assignments: [ '0' ],
     });
 })
   
-// the list of groups a student is in
+// The list of groups a student is in
 router.get('/:id/groups', (req, res) => {
     res.json({
         groups: [ '0' ],
diff --git a/backend/src/routes/submission.ts b/backend/src/routes/submission.ts
index 8d09cf8e..98acc842 100644
--- a/backend/src/routes/submission.ts
+++ b/backend/src/routes/submission.ts
@@ -1,7 +1,7 @@
 import express from 'express'
 const router = express.Router();
 
-// root endpoint used to search objects
+// Root endpoint used to search objects
 router.get('/', (req, res) => {
     res.json({
         submissions: [
@@ -11,7 +11,7 @@ router.get('/', (req, res) => {
     });
 });
 
-// information about an submission with id 'id'
+// Information about an submission with id 'id'
 router.get('/:id', (req, res) => {
     res.json({
         id: req.params.id,
diff --git a/backend/src/routes/teacher.ts b/backend/src/routes/teacher.ts
index 37b3b04b..f9de3aa5 100644
--- a/backend/src/routes/teacher.ts
+++ b/backend/src/routes/teacher.ts
@@ -1,7 +1,7 @@
 import express from 'express'
 const router = express.Router();
 
-// root endpoint used to search objects
+// Root endpoint used to search objects
 router.get('/', (req, res) => {
     res.json({
         teachers: [
@@ -11,7 +11,7 @@ router.get('/', (req, res) => {
     });
 });
 
-// information about a teacher
+// Information about a teacher
 router.get('/:id', (req, res) => {
     res.json({
         id: req.params.id,
@@ -27,7 +27,7 @@ router.get('/:id', (req, res) => {
     });
 })
 
-// the questions students asked a teacher
+// The questions students asked a teacher
 router.get('/:id/questions', (req, res) => {
     res.json({
         questions: [
@@ -36,7 +36,7 @@ router.get('/:id/questions', (req, res) => {
     });
 });
 
-// invitations to other classes a teacher received
+// Invitations to other classes a teacher received
 router.get('/:id/invitations', (req, res) => {
     res.json({
         invitations: [
@@ -45,7 +45,7 @@ router.get('/:id/invitations', (req, res) => {
     });
 });
 
-// a list with ids of classes a teacher is in
+// A list with ids of classes a teacher is in
 router.get('/:id/classes', (req, res) => {
     res.json({
         classes: [
diff --git a/backend/tests/data/users.test.ts b/backend/tests/data/users.test.ts
index c7cc875d..a982151e 100644
--- a/backend/tests/data/users.test.ts
+++ b/backend/tests/data/users.test.ts
@@ -18,7 +18,7 @@ describe("StudentRepository", () => {
     it("should return the queried student after he was added", async () => {
         await studentRepository.insert(new Student(username, firstName, lastName));
 
-        let retrievedStudent = await studentRepository.findByUsername(username);
+        const retrievedStudent = await studentRepository.findByUsername(username);
         expect(retrievedStudent).toBeTruthy();
         expect(retrievedStudent?.firstName).toBe(firstName);
         expect(retrievedStudent?.lastName).toBe(lastName);
@@ -27,7 +27,7 @@ describe("StudentRepository", () => {
     it("should no longer return the queried student after he was removed again", async () => {
         await studentRepository.deleteByUsername(username);
 
-        let retrievedStudent = await studentRepository.findByUsername(username);
+        const retrievedStudent = await studentRepository.findByUsername(username);
         expect(retrievedStudent).toBeNull();
     });
 });