message: ParameterControls fix
diff: @@ -55,7 +55,7 @@ export class ParameterControls<P extends PD.Params> extends React.PureComponent<
  if (!ctrls) return null;
  if (category) {
  - return [<ExpandGroup header={category}>{ctrls}</ExpandGroup>];
  + return [<ExpandGroup key={category} header={category}>{ctrls}</ExpandGroup>];
  }
  return ctrls;
  }
  