message: fix: item.warnings is optional
diff: @@ -24,7 +24,7 @@ function NavigationTree(props) {
  id={
  item.id
  }
  - meta={item.warnings.map(warning => <Meta warning={warning}/>)}
  + meta={(item.warnings || []).map(warning => <Meta warning={warning}/>)}
  name={item.manifest.displayName}
  onClick={props.onItemClick}
  onScrollRequest={props.onScrollRequest}
  