[editor] Fix combined property logic and copy values before setting them

The copy is needed to not have cross references between elements.

projects/common/util/copy.ts

+export abstract class Copy {
+  static getCopy(objectToCopy: any): any {
+    if (objectToCopy instanceof Array) {
+      return [...objectToCopy];
+    }
+    if (objectToCopy instanceof Object) {
+      return { ...objectToCopy };
+    }
+    return objectToCopy;
+  }
+}

projects/editor/src/app/components/unit-view/page-view/properties-panel/element-model-properties.component.ts

@@ -31,7 +31,10 @@ export class ElementModelPropertiesComponent {
 
   addOption(property: string, value: string): void {
     (this.combinedProperties[property] as string[]).push(value);
-    this.updateModel.emit({ property: property, value: this.combinedProperties[property] as string[] });
+    this.updateModel.emit({
+      property: property,
+      value: [...this.combinedProperties[property] as string[]]
+    });
   }
 
   reorderOptions(property: string, event: CdkDragDrop<string[]>): void {

projects/editor/src/app/components/unit-view/page-view/properties-panel/element-properties.component.ts

@@ -70,9 +70,8 @@ export class ElementPropertiesComponent implements OnInit, OnDestroy {
         Object.keys(this.combinedProperties).forEach((property: keyof UIElement) => {
           if (Object.prototype.hasOwnProperty.call(flattenedSelectedElements[i], property)) {
             if (Array.isArray(flattenedSelectedElements[i][property])) {
-              if (flattenedSelectedElements[i][property]!.toString() === this.combinedProperties[property]!.toString()) {
-                // @ts-ignore TODO
-                flattenedSelectedElements[property] = flattenedSelectedElements[i][property];
+              if (flattenedSelectedElements[i][property]?.toString() === this.combinedProperties[property]?.toString()) {
+                this.combinedProperties[property] = flattenedSelectedElements[i][property];
               }
             }
             if (flattenedSelectedElements[i][property] !== this.combinedProperties[property]) {

projects/editor/src/app/services/unit.service.ts

@@ -25,6 +25,7 @@ import { LikertElementRow } from '../../../../common/ui-elements/likert/likert-e
 import { SelectionService } from './selection.service';
 import { ElementFactory } from '../../../../common/util/element.factory';
 import { ClozeParser } from '../util/cloze-parser';
+import { Copy } from '../../../../common/util/copy';
 
 @Injectable({
   providedIn: 'root'
@@ -260,7 +261,7 @@ export class UnitService {
       } else if (property === 'text' && element.type === 'cloze') {
         element.setProperty('parts', ClozeParser.createClozeParts(value as string, this.idService));
       } else {
-        element.setProperty(property, value);
+        element.setProperty(property, Copy.getCopy(value));
       }
     }
     this.elementPropertyUpdated.next();