message: add missing React key
diff: @@ -383,10 +383,10 @@ export class SequenceView extends PluginUIComponent<{ defaultMode?: SequenceView
  if (values.mode === 'single') return elem;
  - return <>
  + return <React.Fragment key={i}>
  <div className='msp-sequence-chain-label'>{s.label}</div>
  {elem}
  - </>;
  + </React.Fragment>;
  })}
  </NonEmptySequenceWrapper>
  </div>;
  