message: Fix MappedControl edge case
diff: @@ -1193,7 +1193,8 @@ export class MappedControl extends React.PureComponent<ParamProps<PD.Mapped<any>
  }
  render() {
  - const value: PD.Mapped<any>['defaultValue'] = this.props.value;
  + const value: PD.Mapped<any>['defaultValue'] = this.props.value || this.props.param.defaultValue;
  +
  const param = this.props.param.map(value.name);
  const label = this.props.param.label || camelCaseToWords(this.props.name);
  const Mapped = controlFor(param);
  