Fix ToggleButton initialization

... to create a new reference for options property.

projects/common/models/elements/compound-elements/cloze/cloze-child-elements/toggle-button.ts

@@ -20,7 +20,7 @@ export class ToggleButtonElement extends InputElement {
 
   constructor(element: Partial<ToggleButtonElement>) {
     super({ height: 30, ...element });
-    if (element.options) this.options = element.options;
+    if (element.options) this.options = [...element.options];
     if (element.strikeOtherOptions) this.strikeOtherOptions = element.strikeOtherOptions;
     if (element.strikeSelectedOption) this.strikeSelectedOption = element.strikeSelectedOption;
     if (element.verticalOrientation) this.verticalOrientation = element.verticalOrientation;