fix(VariantManagement): fix dirty-state and readOnly behavior (#6628)

Fixes #6622
Fixes #6617

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## Pull Request Checklist
- [x] Reviewed the [Contributing
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Author: superdyzio

packages/main/src/components/VariantManagement/index.tsx

@@ -317,8 +317,7 @@ const VariantManagement = forwardRef<HTMLDivElement, VariantManagementPropTypes>
     }
   }, [safeChildrenWithFavorites]);
 
-  // todo: this applies if `readOnly` is set to `false` as well since the value is read via data-attribute and is therefore a string not a boolean
-  const showSaveBtn = dirtyState && !Object.prototype.hasOwnProperty.call(selectedVariant, 'readOnly');
+  const showSaveBtn = dirtyState && selectedVariant && !selectedVariant.readOnly;
 
   return (
     <div className={variantManagementClasses} style={style} {...rest} ref={ref}>