diff --git a/eslint.config.ts b/eslint.config.ts
index 30e8fe2f..68e264b8 100644
--- a/eslint.config.ts
+++ b/eslint.config.ts
@@ -71,7 +71,7 @@ export default [
             'init-declarations': 'off',
             '@typescript-eslint/init-declarations': 'off',
             'max-params': 'off',
-            '@typescript-eslint/max-params': ['error', { max: 6 }],
+            '@typescript-eslint/max-params': 'off',
             '@typescript-eslint/member-ordering': 'error',
             '@typescript-eslint/method-signature-style': 'off', // Don't care about TypeScript strict mode.
             '@typescript-eslint/naming-convention': [
@@ -87,6 +87,7 @@ export default [
                     modifiers: ['const'],
                     format: ['camelCase', 'UPPER_CASE'],
                     trailingUnderscore: 'allow',
+                    leadingUnderscore: 'allow',
                 },
                 {
                     // Enforce that private members are prefixed with an underscore
diff --git a/frontend/src/queries/submissions.ts b/frontend/src/queries/submissions.ts
index 812e5fe5..6e218003 100644
--- a/frontend/src/queries/submissions.ts
+++ b/frontend/src/queries/submissions.ts
@@ -1,20 +1,22 @@
-import { SubmissionController, type SubmissionResponse } from "@/controllers/submissions";
-import type { SubmissionDTO } from "@dwengo-1/common/interfaces/submission";
+import { SubmissionController, type SubmissionResponse } from '@/controllers/submissions';
+import type { SubmissionDTO } from '@dwengo-1/common/interfaces/submission';
 import {
     QueryClient,
     useMutation,
+    type UseMutationReturnType,
     useQuery,
     useQueryClient,
-    type UseMutationReturnType,
     type UseQueryReturnType,
-} from "@tanstack/vue-query";
-import { computed, toValue, type MaybeRefOrGetter } from "vue";
-import { LEARNING_PATH_KEY } from "@/queries/learning-paths.ts";
-import { LEARNING_OBJECT_KEY } from "@/queries/learning-objects.ts";
-import type { Language } from "@dwengo-1/common/util/language";
+} from '@tanstack/vue-query';
+import { computed, type MaybeRefOrGetter, toValue } from 'vue';
+import { LEARNING_PATH_KEY } from '@/queries/learning-paths.ts';
+import { LEARNING_OBJECT_KEY } from '@/queries/learning-objects.ts';
+import { Language } from '@dwengo-1/common/util/language';
 
 export const SUBMISSION_KEY = "submissions";
 
+type SubmissionQueryKey = ["submission", string, Language | undefined, number, string, number, number, number];
+
 function submissionQueryKey(
     hruid: string,
     language: Language,
@@ -23,7 +25,7 @@ function submissionQueryKey(
     assignmentNumber: number,
     groupNumber: number,
     submissionNumber: number,
-) {
+): SubmissionQueryKey {
     return ["submission", hruid, language, version, classid, assignmentNumber, groupNumber, submissionNumber];
 }
 
@@ -39,19 +41,21 @@ export async function invalidateAllSubmissionKeys(
 ): Promise<void> {
     const keys = ["submission"];
 
-    for (const key of keys) {
-        const queryKey = [
-            key,
-            hruid,
-            language,
-            version,
-            classid,
-            assignmentNumber,
-            groupNumber,
-            submissionNumber,
-        ].filter((arg) => arg !== undefined);
-        await queryClient.invalidateQueries({ queryKey: queryKey });
-    }
+    await Promise.all(
+        keys.map(async (key) => {
+            const queryKey = [
+                key,
+                hruid,
+                language,
+                version,
+                classid,
+                assignmentNumber,
+                groupNumber,
+                submissionNumber,
+            ].filter((arg) => arg !== undefined);
+            return queryClient.invalidateQueries({ queryKey: queryKey });
+        })
+    )
 
     await queryClient.invalidateQueries({
         queryKey: ["submissions", hruid, language, version, classid, assignmentNumber, groupNumber].filter(
diff --git a/frontend/src/utils/array-utils.ts b/frontend/src/utils/array-utils.ts
index cba3291e..9a4ce828 100644
--- a/frontend/src/utils/array-utils.ts
+++ b/frontend/src/utils/array-utils.ts
@@ -1,4 +1,4 @@
-export function copyArrayWith<T>(index: number, newValue: T, array: T[]) {
+export function copyArrayWith<T>(index: number, newValue: T, array: T[]): T[] {
     const copy = [...array];
     copy[index] = newValue;
     return copy;
diff --git a/frontend/src/utils/deep-equals.ts b/frontend/src/utils/deep-equals.ts
index 2edc1be2..4434f911 100644
--- a/frontend/src/utils/deep-equals.ts
+++ b/frontend/src/utils/deep-equals.ts
@@ -3,7 +3,7 @@ export function deepEquals<T>(a: T, b: T): boolean {
         return true;
     }
 
-    if (typeof a !== "object" || typeof b !== "object" || a == null || b == null) {
+    if (typeof a !== "object" || typeof b !== "object" || a === null || b === null) {
         return false;
     }
 
diff --git a/frontend/src/views/learning-paths/LearningPathPage.vue b/frontend/src/views/learning-paths/LearningPathPage.vue
index 953e70d1..2abb753e 100644
--- a/frontend/src/views/learning-paths/LearningPathPage.vue
+++ b/frontend/src/views/learning-paths/LearningPathPage.vue
@@ -1,20 +1,20 @@
 <script setup lang="ts">
-    import { Language } from "@/data-objects/language.ts";
-    import type { LearningPath } from "@/data-objects/learning-paths/learning-path.ts";
-    import { computed, type ComputedRef, ref } from "vue";
-    import type { LearningObject } from "@/data-objects/learning-objects/learning-object.ts";
-    import { useRoute, useRouter } from "vue-router";
-    import LearningObjectView from "@/views/learning-paths/learning-object/LearningObjectView.vue";
-    import { useI18n } from "vue-i18n";
-    import LearningPathSearchField from "@/components/LearningPathSearchField.vue";
-    import { useGetLearningPathQuery } from "@/queries/learning-paths.ts";
-    import { useLearningObjectListForPathQuery } from "@/queries/learning-objects.ts";
-    import UsingQueryResult from "@/components/UsingQueryResult.vue";
-    import authService from "@/services/auth/auth-service.ts";
-    import { LearningPathNode } from "@/data-objects/learning-paths/learning-path-node.ts";
-    import LearningPathGroupSelector from "@/views/learning-paths/LearningPathGroupSelector.vue";
+import { Language } from '@/data-objects/language.ts';
+import type { LearningPath } from '@/data-objects/learning-paths/learning-path.ts';
+import { computed, type ComputedRef, ref } from 'vue';
+import type { LearningObject } from '@/data-objects/learning-objects/learning-object.ts';
+import { useRoute, useRouter } from 'vue-router';
+import LearningObjectView from '@/views/learning-paths/learning-object/LearningObjectView.vue';
+import { useI18n } from 'vue-i18n';
+import LearningPathSearchField from '@/components/LearningPathSearchField.vue';
+import { useGetLearningPathQuery } from '@/queries/learning-paths.ts';
+import { useLearningObjectListForPathQuery } from '@/queries/learning-objects.ts';
+import UsingQueryResult from '@/components/UsingQueryResult.vue';
+import authService from '@/services/auth/auth-service.ts';
+import { LearningPathNode } from '@/data-objects/learning-paths/learning-path-node.ts';
+import LearningPathGroupSelector from '@/views/learning-paths/LearningPathGroupSelector.vue';
 
-    const router = useRouter();
+const router = useRouter();
     const route = useRoute();
     const { t } = useI18n();
 
@@ -40,6 +40,7 @@
                 classId: query.value.classId,
             };
         }
+        return undefined
     });
 
     const learningPathQueryResult = useGetLearningPathQuery(props.hruid, props.language, forGroup);
@@ -108,15 +109,15 @@
 
     const forGroupQueryParam = computed<number | undefined>({
         get: () => route.query.forGroup,
-        set: (value: number | undefined) => {
-            let query = structuredClone(route.query);
+        set: async (value: number | undefined) => {
+            const query = structuredClone(route.query);
             query.forGroup = value;
-            router.push({ query });
+            await router.push({ query });
         },
     });
 
-    function assign() {
-        router.push({
+    async function assign(): Promise<void> {
+        await router.push({
             path: "/assignment/create",
             query: {
                 hruid: props.hruid,
diff --git a/frontend/src/views/learning-paths/learning-object/LearningObjectView.vue b/frontend/src/views/learning-paths/learning-object/LearningObjectView.vue
index 4974083e..9df3355b 100644
--- a/frontend/src/views/learning-paths/learning-object/LearningObjectView.vue
+++ b/frontend/src/views/learning-paths/learning-object/LearningObjectView.vue
@@ -9,7 +9,7 @@
     import LearningObjectContentView from "@/views/learning-paths/learning-object/content/LearningObjectContentView.vue";
     import LearningObjectSubmissionsView from "@/views/learning-paths/learning-object/submissions/LearningObjectSubmissionsView.vue";
 
-    const isStudent = computed(() => authService.authState.activeRole === "student");
+    const _isStudent = computed(() => authService.authState.activeRole === "student");
 
     const props = defineProps<{
         hruid: string;
diff --git a/frontend/src/views/learning-paths/learning-object/content/LearningObjectContentView.vue b/frontend/src/views/learning-paths/learning-object/content/LearningObjectContentView.vue
index 0ddde28a..df363aa7 100644
--- a/frontend/src/views/learning-paths/learning-object/content/LearningObjectContentView.vue
+++ b/frontend/src/views/learning-paths/learning-object/content/LearningObjectContentView.vue
@@ -9,18 +9,19 @@
         submissionData?: SubmissionData;
     }>();
 
-    const emit = defineEmits<{
-        (e: "update:submissionData", value: SubmissionData): void;
-    }>();
+    const emit = defineEmits<(e: "update:submissionData", value: SubmissionData) => void>();
 
     const submissionData = computed<SubmissionData | undefined>({
         get: () => props.submissionData,
-        set: (v?: SubmissionData) => (v ? emit("update:submissionData", v) : undefined),
+        set: (v?: SubmissionData): void => {
+          if (v)
+            emit("update:submissionData", v)
+        },
     });
 
     function forEachQuestion(
         doAction: (questionIndex: number, questionName: string, questionType: string, questionElement: Element) => void,
-    ) {
+    ): void {
         const questions = document.querySelectorAll(".gift-question");
         questions.forEach((question) => {
             const name = question.id.match(/gift-q(\d+)/)?.[1];
@@ -45,8 +46,8 @@
         });
     }
 
-    function setAnswers(answers: SubmissionData) {
-        forEachQuestion((index, name, type, element) => {
+    function setAnswers(answers: SubmissionData): void {
+        forEachQuestion((index, _name, type, element) => {
             const answer = answers[index];
             if (answer !== null && answer !== undefined) {
                 getGiftAdapterForType(type)?.setAnswer(element, answer);
@@ -57,7 +58,7 @@
         submissionData.value = answers;
     }
 
-    onMounted(() =>
+    onMounted(async () =>
         nextTick(() => {
             attachQuestionListeners();
             setAnswers(props.submissionData ?? []);
diff --git a/frontend/src/views/learning-paths/learning-object/submissions/LearningObjectSubmissionsTable.vue b/frontend/src/views/learning-paths/learning-object/submissions/LearningObjectSubmissionsTable.vue
index ee680725..2a6da999 100644
--- a/frontend/src/views/learning-paths/learning-object/submissions/LearningObjectSubmissionsTable.vue
+++ b/frontend/src/views/learning-paths/learning-object/submissions/LearningObjectSubmissionsTable.vue
@@ -8,9 +8,7 @@
     const props = defineProps<{
         allSubmissions: SubmissionDTO[];
     }>();
-    const emit = defineEmits<{
-        (e: "submission-selected", submission: SubmissionDTO): void;
-    }>();
+    const emit = defineEmits<(e: "submission-selected", submission: SubmissionDTO) => void>();
 
     const headers = computed(() => [
         { title: "#", value: "submissionNo", width: "50px" },
@@ -30,7 +28,7 @@
             })),
     );
 
-    function selectSubmission(submission: SubmissionDTO) {
+    function selectSubmission(submission: SubmissionDTO): void {
         emit("submission-selected", submission);
     }
 </script>
@@ -46,7 +44,7 @@
                 hide-default-footer
                 :no-data-text="t('noSubmissionsYet')"
             >
-                <template v-slot:item.action="{ item }">
+                <template v-slot:[`item.action`]="{ item }">
                     <v-btn
                         density="compact"
                         variant="plain"
diff --git a/frontend/src/views/learning-paths/learning-object/submissions/LearningObjectSubmissionsView.vue b/frontend/src/views/learning-paths/learning-object/submissions/LearningObjectSubmissionsView.vue
index ee541eb2..5a7fa9d2 100644
--- a/frontend/src/views/learning-paths/learning-object/submissions/LearningObjectSubmissionsView.vue
+++ b/frontend/src/views/learning-paths/learning-object/submissions/LearningObjectSubmissionsView.vue
@@ -18,9 +18,7 @@
         version: number;
         group: { forGroup: number; assignmentNo: number; classId: string };
     }>();
-    const emit = defineEmits<{
-        (e: "update:submissionData", value: SubmissionData): void;
-    }>();
+    const emit = defineEmits<(e: "update:submissionData", value: SubmissionData) => void>();
 
     const submissionQuery = useSubmissionsQuery(
         () => props.hruid,
@@ -32,11 +30,11 @@
         () => true,
     );
 
-    function emitSubmissionData(submissionData: SubmissionData) {
+    function emitSubmissionData(submissionData: SubmissionData): void {
         emit("update:submissionData", submissionData);
     }
 
-    function emitSubmission(submission: SubmissionDTO) {
+    function emitSubmission(submission: SubmissionDTO): void {
         emitSubmissionData(JSON.parse(submission.content));
     }
 
diff --git a/frontend/src/views/learning-paths/learning-object/submissions/SubmitButton.vue b/frontend/src/views/learning-paths/learning-object/submissions/SubmitButton.vue
index ca2c98df..1d36f342 100644
--- a/frontend/src/views/learning-paths/learning-object/submissions/SubmitButton.vue
+++ b/frontend/src/views/learning-paths/learning-object/submissions/SubmitButton.vue
@@ -25,9 +25,9 @@
 
     const {
         isPending: submissionIsPending,
-        isError: submissionFailed,
-        error: submissionError,
-        isSuccess: submissionSuccess,
+        // - isError: submissionFailed,
+        // - error: submissionError,
+        // - isSuccess: submissionSuccess,
         mutate: submitSolution,
     } = useCreateSubmissionMutation();
 
@@ -47,11 +47,11 @@
     });
 
     function submitCurrentAnswer(): void {
-        const { forGroup, assignmentNo, classId } = props.group!;
+        const { forGroup, assignmentNo, classId } = props.group;
         const currentUser: UserProfile = authService.authState.user!.profile;
         const learningObjectIdentifier: LearningObjectIdentifierDTO = {
             hruid: props.hruid,
-            language: props.language as Language,
+            language: props.language,
             version: props.version,
         };
         const submitter: StudentDTO = {