_civicrm_api3_generic_get_metadata_options() makes invalid civicrm_api() call

In _civicrm_api3_generic_get_metadata_options() we do

$pseudoParams['class'] = $fieldSpec['pseudoconstant'];
$pseudoParams['version'] = 3;

This will pass a value of (string) '3ontactType' as $params to civicrm_api(), which will then be rejected as $params is not an array.

Observed developing Mailing,Create API extension; origin was -

• civicrm_api('contact', 'getfields', array('version' => 3, 'action' => 'get');
• _civicrm_api3_generic_getfields
• _civicrm_api3_generic_get_metadata_options