title: ng-multiselect-dropdown - TypeError: Cannot read property 'idField' of undefined
body: <p>Followed steps as per 
  <a href="https://www.npmjs.com/package/ng-multiselect-dropdown" rel="noreferrer">https://www.npmjs.com/package/ng-multiselect-dropdown</a> for angular 9</p>
  
  <p>received below error in browser console</p>
  
  <p>TypeError: Cannot read property 'idField' of undefined</p>