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.

const innerHTMLContent = innerHTML.__html;
      if (innerHTMLContent != null && innerHTMLContent !== '') {
        DOMLazyTree.queueHTML(lazyTree, innerHTMLContent);
      }
    } else {
      var contentToUse = CONTENT_TYPES[typeof props.children]
        ? props.children
        : null;
      var childrenToUse = contentToUse != null ? null : props.children;
      
      if (contentToUse != null) {
        
        
        
        
        if (contentToUse !== '') {
          if (__DEV__) {
            setAndValidateContentChildDev.call(this, contentToUse);
          }
          DOMLazyTree.queueText(lazyTree, contentToUse);
        }
      } else if (childrenToUse != null) {
        var mountImages = this.mountChildren(
          childrenToUse,
          transaction,
          context,
        );
        for (var i = 0; i < mountImages.length; i++) {
          DOMLazyTree.queueChild(lazyTree, mountImages[i]);
        }