refactor computed property to native getter with compatibility layer

Author: jelhan

addon/components/bs-form/element.js

@@ -1,12 +1,13 @@
 import BsFormElement from 'ember-bootstrap/components/bs-form/element';
+import { dependentKeyCompat } from '@ember/object/compat';
 
 export default class BsFormElementWithChangesetValidationsSupport extends BsFormElement {
   '__ember-bootstrap_subclass' = true;
 
+  @dependentKeyCompat
   get errors() {
-    return [
-      this.model.error[this.property]?.validation
-    ];
+    let error = this.model.error[this.property]?.validation;
+    return error ? [error] : [];
   }
 
   get hasValidator() {