Steps to reproduce

1.  Configure tabbedForm as described in documentation

   form:
     $type: tabbedForm
     tabs:
       firstTab:
         fields:
           foo:
             label: foo
             $type: textField
       secondTab:
         fields:
           bar:
             label: bar
             $type: textField
             required: true

2.  Open definitions app and check definition

Expected results

No errors are shown and the dialog works ok

Actual results

The dialog works ok but there's a major error in definition

Workaround

Development notes