Validation for radio inputs don't work for me

I'm building a form with the drupal forms api. Validation works well for all my other fields. But I've started to try and work with radio buttons too now. It doesn't matter if I click on a radio option, the validation returns always 'color is required'.

// Form build method code
$form['birthdate'] = [
  '#type' => 'date',
  '#title' => $this->t('Your date of birth'),
  '#date_date_format' => 'd-m-Y',
];

$form['color_select'] = [
  '#type' => 'radios',
  '#title' => $this->t('Pick a color'),
  '#options' => [
    'blue' => $this->t('Blue'),
    'white' => $this->t('White'),
    'black' => $this->t('Black'),
    // 'other' => $this->t('Other'),
  ],
  '#attributes' => [
    'id' => 'color_select',
    'name' => 'field_color_select',
  ],
  '#states' => [
    'enabled' => [
      ':input[name="field_custom_color"]' => ['value' => ''],
    ],
  ],
];

// Form validator method code
if ($form_state->getValue('birthdate') == '') {
  $form_state->setErrorByName('birthdate', $this->t('Date of birth is required'));
}
if ($form_state->getValue('color_select') == '') {
  $form_state->setErrorByName('color_select', $this->t('Color is required'));
}

I thought that the getValue(name) and setErrorByname(name) have to the same as $form[name] =[]; to make it work, but for the radio buttons field, it doesn't.

I managed to get it working like this:

$form['color_select'] = [
  '#type' => 'radios',
  '#title' => $this->t('Pick a color'),
  '#options' => [
    'blue' => $this->t('Blue'),
    'white' => $this->t('White'),
    'black' => $this->t('Black'),
    // 'other' => $this->t('Other'),
  ],
  '#attributes' => [
    'id' => 'color_select',
    'name' => 'color_select',
  ],
  '#states' => [
    'checked' => [
      ':input[name="color_select"]' => [
        ['value' => 'blue'],
        'or',
        ['value' => 'white'],
        'or',
        ['value' => 'black'],
      ],
    ],
  ],
];

Although I'm not sure how it works now. Does it actually set the radio button on checked when the value is one of the given value ones?