title: Expected a value of type 'SkDeletable', but got one of type 'Null'
body: <p>I have updated my flutter project from 1.26.3 to 2.1.0. Since then I am facing some issue. I am getting error as &quot;Expected a value of type 'SkDeletable', but got one of type 'Null'&quot;.</p>
  <p>Does anybody knows what is related with?</p>