diff --git a/src/components/VtkObliqueView.vue b/src/components/VtkObliqueView.vue
index 4ae8f8e8..57fdd9f8 100644
--- a/src/components/VtkObliqueView.vue
+++ b/src/components/VtkObliqueView.vue
@@ -219,7 +219,7 @@ export default defineComponent({
       get: () => windowingStore.getConfig(viewID.value, curImageID.value),
       set: (newValue) => {
         const imageID = curImageID.value;
-        if (imageID !== null && newValue != null) {
+        if (imageID != null && newValue != null) {
           windowingStore.updateConfig(viewID.value, imageID, newValue);
         }
       },
@@ -229,7 +229,7 @@ export default defineComponent({
     const windowLevel = computed(() => wlConfig.value?.level);
     const dicomInfo = computed(() => {
       if (
-        curImageID.value !== null &&
+        curImageID.value != null &&
         curImageID.value in dicomStore.imageIDToVolumeKey
       ) {
         const volumeKey = dicomStore.imageIDToVolumeKey[curImageID.value];
diff --git a/src/components/VtkTwoView.vue b/src/components/VtkTwoView.vue
index 3b8c921a..94ee61c4 100644
--- a/src/components/VtkTwoView.vue
+++ b/src/components/VtkTwoView.vue
@@ -333,7 +333,7 @@ export default defineComponent({
       get: () => windowingStore.getConfig(viewID.value, curImageID.value),
       set: (newValue) => {
         const imageID = curImageID.value;
-        if (imageID !== null && newValue != null) {
+        if (imageID != null && newValue != null) {
           windowingStore.updateConfig(viewID.value, imageID, newValue);
         }
       },
@@ -346,7 +346,7 @@ export default defineComponent({
     );
     const dicomInfo = computed(() => {
       if (
-        curImageID.value !== null &&
+        curImageID.value != null &&
         curImageID.value in dicomStore.imageIDToVolumeKey
       ) {
         const volumeKey = dicomStore.imageIDToVolumeKey[curImageID.value];
@@ -388,7 +388,7 @@ export default defineComponent({
     // --- setters --- //
 
     const setSlice = (slice: number) => {
-      if (curImageID.value !== null) {
+      if (curImageID.value != null) {
         viewSliceStore.updateConfig(viewID.value, curImageID.value, {
           slice,
         });
diff --git a/src/components/tools/SliceScrollTool.vue b/src/components/tools/SliceScrollTool.vue
index cd04de82..0feaf6c5 100644
--- a/src/components/tools/SliceScrollTool.vue
+++ b/src/components/tools/SliceScrollTool.vue
@@ -96,7 +96,7 @@ export default defineComponent({
         range.step,
         () => scrollVal.value,
         (slice) => {
-          if (currentImageID.value !== null) {
+          if (currentImageID.value != null) {
             viewSliceStore.updateConfig(viewID.value, currentImageID.value, {
               slice,
             });
diff --git a/src/composables/usePersistCameraConfig.ts b/src/composables/usePersistCameraConfig.ts
index 2fdfb5ee..5bddbe12 100644
--- a/src/composables/usePersistCameraConfig.ts
+++ b/src/composables/usePersistCameraConfig.ts
@@ -1,12 +1,13 @@
 import { manageVTKSubscription } from '@/src/composables/manageVTKSubscription';
 import { Ref } from 'vue';
+import { Maybe } from '@/src/types';
 import { CameraConfig } from '../store/view-configs/types';
 import { vtkLPSViewProxy } from '../types/vtk-types';
 import useViewCameraStore from '../store/view-configs/camera';
 
 export function usePersistCameraConfig(
   viewID: Ref<string>,
-  dataID: Ref<string | null>,
+  dataID: Ref<Maybe<string>>,
   viewProxy: Ref<vtkLPSViewProxy>,
   ...toPersist: (keyof CameraConfig)[]
 ) {
@@ -19,7 +20,7 @@ export function usePersistCameraConfig(
 
   if (toPersist.indexOf('position') > -1) {
     persist.push(() => {
-      if (dataID.value !== null && persistCameraConfig) {
+      if (dataID.value != null && persistCameraConfig) {
         viewCameraStore.updateConfig(viewID.value, dataID.value, {
           position: viewProxy.value.getCamera().getPosition(),
         });
@@ -28,7 +29,7 @@ export function usePersistCameraConfig(
   }
   if (toPersist.indexOf('viewUp') > -1) {
     persist.push(() => {
-      if (dataID.value !== null && persistCameraConfig) {
+      if (dataID.value != null && persistCameraConfig) {
         viewCameraStore.updateConfig(viewID.value, dataID.value, {
           viewUp: viewProxy.value.getCamera().getViewUp(),
         });
@@ -37,7 +38,7 @@ export function usePersistCameraConfig(
   }
   if (toPersist.indexOf('focalPoint') > -1) {
     persist.push(() => {
-      if (dataID.value !== null && persistCameraConfig) {
+      if (dataID.value != null && persistCameraConfig) {
         viewCameraStore.updateConfig(viewID.value, dataID.value, {
           focalPoint: viewProxy.value.getCamera().getFocalPoint(),
         });
@@ -46,7 +47,7 @@ export function usePersistCameraConfig(
   }
   if (toPersist.indexOf('directionOfProjection') > -1) {
     persist.push(() => {
-      if (dataID.value !== null && persistCameraConfig) {
+      if (dataID.value != null && persistCameraConfig) {
         viewCameraStore.updateConfig(viewID.value, dataID.value, {
           directionOfProjection: viewProxy.value
             .getCamera()
@@ -57,7 +58,7 @@ export function usePersistCameraConfig(
   }
   if (toPersist.indexOf('parallelScale') > -1) {
     persist.push(() => {
-      if (dataID.value !== null && persistCameraConfig) {
+      if (dataID.value != null && persistCameraConfig) {
         viewCameraStore.updateConfig(viewID.value, dataID.value, {
           parallelScale: viewProxy.value.getCamera().getParallelScale(),
         });
diff --git a/src/composables/useSceneBuilder.ts b/src/composables/useSceneBuilder.ts
index 71b1dd99..3b95c190 100644
--- a/src/composables/useSceneBuilder.ts
+++ b/src/composables/useSceneBuilder.ts
@@ -1,11 +1,12 @@
 import vtkAbstractRepresentationProxy from '@kitware/vtk.js/Proxy/Core/AbstractRepresentationProxy';
 import { computed, Ref, watch } from 'vue';
+import { Maybe } from '@/src/types';
 import { useViewStore } from '../store/views';
 import { vtkLPSViewProxy } from '../types/vtk-types';
 import { arrayEquals } from '../utils';
 
 interface Scene {
-  baseImage?: Ref<string | null>;
+  baseImage?: Ref<Maybe<string>>;
   labelmaps?: Ref<string[]>;
   layers?: Ref<string[]>;
   models?: Ref<string[]>;
diff --git a/src/store/tools/crop.ts b/src/store/tools/crop.ts
index 9fe59a13..73e100a1 100644
--- a/src/store/tools/crop.ts
+++ b/src/store/tools/crop.ts
@@ -9,6 +9,7 @@ import { MaybeRef } from '@vueuse/core';
 import { vec3 } from 'gl-matrix';
 import { defineStore } from 'pinia';
 import { arrayEqualsWithComparator } from '@/src/utils';
+import { Maybe } from '@/src/types';
 import { useImageStore } from '../datasets-images';
 import { LPSCroppingPlanes } from '../../types/crop';
 import { ImageMetadata } from '../../types/image';
@@ -89,7 +90,7 @@ export const useCropStore = defineStore('crop', () => {
     croppingByImageID: {} as Record<string, LPSCroppingPlanes>,
   });
 
-  const getComputedVTKPlanes = (imageID: MaybeRef<string | null>) =>
+  const getComputedVTKPlanes = (imageID: MaybeRef<Maybe<string>>) =>
     computed(() => {
       const id = unref(imageID);
       if (id && id in state.croppingByImageID && id in imageStore.metadata) {
diff --git a/src/store/tools/paint.ts b/src/store/tools/paint.ts
index e7716e65..0a96dffc 100644
--- a/src/store/tools/paint.ts
+++ b/src/store/tools/paint.ts
@@ -15,7 +15,7 @@ export const usePaintToolStore = defineStore('paint', () => {
   type _This = ReturnType<typeof usePaintToolStore>;
 
   const activeMode = ref(PaintMode.CirclePaint);
-  const activeSegmentGroupID = ref<string | null>(null);
+  const activeSegmentGroupID = ref<Maybe<string>>(null);
   const activeSegment = ref<Maybe<number>>(null);
   const brushSize = ref(DEFAULT_BRUSH_SIZE);
   const strokePoints = ref<vec3[]>([]);
@@ -48,7 +48,7 @@ export const usePaintToolStore = defineStore('paint', () => {
   /**
    * Sets the active labelmap.
    */
-  function setActiveLabelmap(segmentGroupID: string | null) {
+  function setActiveLabelmap(segmentGroupID: Maybe<string>) {
     activeSegmentGroupID.value = segmentGroupID;
   }
 
@@ -57,7 +57,7 @@ export const usePaintToolStore = defineStore('paint', () => {
    *
    * If a labelmap exists, pick the first one. If no labelmap exists, create one.
    */
-  function setActiveLabelmapFromImage(imageID: string | null) {
+  function setActiveLabelmapFromImage(imageID: Maybe<string>) {
     if (!imageID) {
       setActiveLabelmap(null);
       return;
@@ -178,7 +178,7 @@ export const usePaintToolStore = defineStore('paint', () => {
   function serialize(state: StateFile) {
     const { paint } = state.manifest.tools;
 
-    paint.activeSegmentGroupID = activeSegmentGroupID.value;
+    paint.activeSegmentGroupID = activeSegmentGroupID.value ?? null;
     paint.brushSize = brushSize.value;
     paint.activeSegment = activeSegment.value;
     paint.labelmapOpacity = labelmapOpacity.value;