This usually means that the user mixed up our lowercase/uppercase naming convention; see https://github.com/facebook/react/pull/3429#issuecomment-85166440.

We could add a message like

> Warning: The tag <commentBox> is unrecognized in this browser. If you meant to render a React component, start its name with an uppercase letter.

We'd check this only once per tag and only in development mode.

nextProps = ReactDOMFiberTextarea.getHostProps(
          domElement,
          nextRawProps,
        );
        updatePayload = [];
        break;
      default:
        lastProps = lastRawProps;
        nextProps = nextRawProps;
        if (
          typeof lastProps.onClick !== 'function' &&
          typeof nextProps.onClick === 'function'
        ) {
          
          trapClickOnNonInteractiveElement(((domElement: any): HTMLElement));
        }
        break;
    }
    assertValidProps(tag, nextProps);
    var propKey;
    var styleName;
    var styleUpdates = null;
    for (propKey in lastProps) {
      if (
        nextProps.hasOwnProperty(propKey) ||
        !lastProps.hasOwnProperty(propKey) ||
        lastProps[propKey] == null
      ) {
        continue;
      }