Right now we validate some of our proptype definitions, but we don't surface the issue until that component class is consumed. We should instead validate these, in `__DEV__` only as warnings when the class in created. This means that a call to `React.PropTypes.onOf('foo')` results in an immediate warning logged.

This is a relatively contained bit of code so would be a good candidate for somebody looking to start contributing to React.

var propType = typeof propValue;
  if (Array.isArray(propValue)) {
    return 'array';
  }
  if (propValue instanceof RegExp) {
    
    
    
    return 'object';
  }
  if (isSymbol(propType, propValue)) {
    return 'symbol';
  }
  return propType;
}
function getPreciseType(propValue) {