React custom Proptype function to check if another prop is defined

component.js

function requiredIfNotHidden(props, propName, componentName) {
  if (!props['hiddenLabel']) {
    let value = props[propName];

    // If no hidden label is set, children are required for accessibility
    if (typeof value === undefined) {
      return new Error(`Required prop '${propName}' was not specified in '${componentName}'. It is required if the 'hiddenLabel' prop is not set for accessibility
    }
  }

  // We're ok if hiddenLabel is set
  return null;
}

Checkbox.propTypes = {
  /** Class string. */
  className: PropTypes.string,
  children: requiredIfNotHidden,