diff --git a/projects/common/util/unit-definition-sanitizer.ts b/projects/common/util/unit-definition-sanitizer.ts
index 19f9e0a36836b070b8ae74ffba7aa10cd7bb94ce..d3f4baea262b3e46eb4d386404d4c496c98ccf3d 100644
--- a/projects/common/util/unit-definition-sanitizer.ts
+++ b/projects/common/util/unit-definition-sanitizer.ts
@@ -94,7 +94,7 @@ export class UnitDefinitionSanitizer {
    */
   private static handleClozeElements(elementList: UIElement[]): void {
     const clozeElements = elementList.filter(element => element.type === 'cloze');
-    if (clozeElements[0].text) {
+    if (clozeElements.length && clozeElements[0].text) {
       clozeElements.forEach((element: Record<string, any>) => {
         const replacedText = element.text.replace(/\\i|\\z|\\r/g, (match: string) => {
           switch (match) {
diff --git a/projects/player/src/app/app.component.ts b/projects/player/src/app/app.component.ts
index 631f07f7fced4e3f05601acf8a6164d50035573a..aa19990ee3603f1ecb1277cf8d4a35dc4ae334c0 100644
--- a/projects/player/src/app/app.component.ts
+++ b/projects/player/src/app/app.component.ts
@@ -13,6 +13,7 @@ import { UnitStateService } from './services/unit-state.service';
 import { MediaPlayerService } from './services/media-player.service';
 import { AlertDialogComponent } from './components/alert-dialog/alert-dialog.component';
 import { Page, Unit } from '../../../common/interfaces/unit';
+import { UnitDefinitionSanitizer } from '../../../common/util/unit-definition-sanitizer';
 
 @Component({
   selector: 'aspect-player',
@@ -59,7 +60,7 @@ export class AppComponent implements OnInit {
       // eslint-disable-next-line no-console
       console.log('player: onStart', message);
       if (message.unitDefinition) {
-        const unitDefinition: Unit = JSON.parse(message.unitDefinition);
+        const unitDefinition: Unit = UnitDefinitionSanitizer.sanitize(JSON.parse(message.unitDefinition));
         this.unitStateElementMapperService.registerDropListValueIds(unitDefinition);
         if (this.metaDataService.verifyUnitDefinitionVersion(unitDefinition.unitDefinitionType)) {
           this.playerConfig = message.playerConfig || {};
diff --git a/projects/player/src/app/components/floating-keyboard/floating-keyboard.component.ts b/projects/player/src/app/components/floating-keyboard/floating-keyboard.component.ts
index f63a013663498193aec0116980932cadfcbce67f..6a9164843d221d2062822216d1848961a29a1bff 100644
--- a/projects/player/src/app/components/floating-keyboard/floating-keyboard.component.ts
+++ b/projects/player/src/app/components/floating-keyboard/floating-keyboard.component.ts
@@ -2,7 +2,7 @@ import {
   Component, EventEmitter, Input, Output
 } from '@angular/core';
 import { CdkOverlayOrigin } from '@angular/cdk/overlay';
-import { InputAssistancePreset } from '../../../../../common/models/uI-element';
+import { InputAssistancePreset } from '../../../../../common/interfaces/elements';
 
 @Component({
   selector: 'aspect-floating-keyboard',
diff --git a/projects/player/src/app/components/key/key.component.ts b/projects/player/src/app/components/key/key.component.ts
index 5bdcfbafcf2625aee3f82d2e03740cc594451640..f00c09d8619b588e31545334e54b5b39837e89cf 100644
--- a/projects/player/src/app/components/key/key.component.ts
+++ b/projects/player/src/app/components/key/key.component.ts
@@ -1,7 +1,7 @@
 import {
   Component, EventEmitter, Input, Output
 } from '@angular/core';
-import { InputAssistancePreset } from '../../../../../common/models/uI-element';
+import { InputAssistancePreset } from '../../../../../common/interfaces/elements';
 
 @Component({
   selector: 'aspect-key',
diff --git a/projects/player/src/app/components/keyboard/keyboard.component.ts b/projects/player/src/app/components/keyboard/keyboard.component.ts
index 128a70db2d8d10c76e63ca062a7b6fb40a8050d5..c7f16f7f0dc9265903b206efb9aadb5094ce1750 100644
--- a/projects/player/src/app/components/keyboard/keyboard.component.ts
+++ b/projects/player/src/app/components/keyboard/keyboard.component.ts
@@ -1,7 +1,7 @@
 import {
   Component, EventEmitter, Input, Output
 } from '@angular/core';
-import { InputAssistancePreset } from '../../../../../common/models/uI-element';
+import { InputAssistancePreset } from '../../../../../common/interfaces/elements';
 
 @Component({
   selector: 'aspect-keyboard',
diff --git a/projects/player/src/app/components/math-keyboard/math-keyboard.component.ts b/projects/player/src/app/components/math-keyboard/math-keyboard.component.ts
index 1f58d4ce86a1690430cf81c47b2f08a0fa407f69..3e153288e2964e1a79d9e58d442ab013ba4aa775 100644
--- a/projects/player/src/app/components/math-keyboard/math-keyboard.component.ts
+++ b/projects/player/src/app/components/math-keyboard/math-keyboard.component.ts
@@ -1,7 +1,7 @@
 import {
   AfterViewInit, Component, EventEmitter, Input, OnInit, Output
 } from '@angular/core';
-import { InputAssistancePreset } from '../../../../../common/models/uI-element';
+import { InputAssistancePreset } from '../../../../../common/interfaces/elements';
 
 @Component({
   selector: 'aspect-math-keyboard',
diff --git a/projects/player/src/app/services/keyboard.service.ts b/projects/player/src/app/services/keyboard.service.ts
index 45e74197e28b6b9a555518e0e9f5047d6eedb86a..b99bcbf34ca4a45b8b51128de4936439ed4ec1d8 100644
--- a/projects/player/src/app/services/keyboard.service.ts
+++ b/projects/player/src/app/services/keyboard.service.ts
@@ -1,7 +1,7 @@
 import { Injectable } from '@angular/core';
 import { TextFieldComponent } from '../../../../common/components/ui-elements/text-field.component';
 import { TextAreaComponent } from '../../../../common/components/ui-elements/text-area.component';
-import { InputAssistancePreset } from '../../../../common/models/uI-element';
+import { InputAssistancePreset } from '../../../../common/interfaces/elements';
 
 @Injectable({
   providedIn: 'root'