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.

if (propKey === STYLE) {
        var lastStyle = lastProps[propKey];
        for (styleName in lastStyle) {
          if (lastStyle.hasOwnProperty(styleName)) {
            if (!styleUpdates) {
              styleUpdates = {};
            }
            styleUpdates[styleName] = '';
          }
        }
      } else if (
        propKey === DANGEROUSLY_SET_INNER_HTML || propKey === CHILDREN
      ) {
        
      } else if (propKey === SUPPRESS_CONTENT_EDITABLE_WARNING) {
        
      } else if (registrationNameModules.hasOwnProperty(propKey)) {
        
        
        
        if (!updatePayload) {
          updatePayload = [];
        }
      } else {
        
        
        (updatePayload = updatePayload || []).push(propKey, null);
      }
    }
    for (propKey in nextProps) {