Handler not working for Search API

The module doesn't work with Search API. Given that this is a temporary module, I recommend any other punters out there having the same problem create a custom function similar to the following:

/**
 * Implements hook_views_data_alter().
 */
function MYMODULE_views_data_alter(array &$data) {

  $data['search_api_index_MYSEARCHINDEX']['FIELDMACHINENAME']['filter'] = [
    'title' => t('MYFIELD filter'),
    'help' => t('MYFIELD date.'),
    'field' => 'FIELDMACHINENAME_value',
    'table' => 'node__FIELDMACHINENAME',
    'id' => 'views_daterange_filters_daterange',
    'field_name' => 'FIELDMACHINENAME',
    'entity_type' => 'node',
  ];
}

The above uses a node entity type. Further substitutions necessary for other types.