Can't query groups using api4

[kenahoo]

I opened the following Stack Exchange question: https://civicrm.stackexchange.com/questions/49150/trouble-with-cv-api-version-3-and-4/49151 and it looks like this is probably an issue with cv's implementation itself.

The following error happens when trying to get (for example) the email address for every user in a given group:

$ cv api4 Contact.get +s email_primary +w 'groups:name = "Current Singers"'

In Api4Query.php line 348:
                               
  Illegal operator for groups