```lisp
(let ((some-gmail-address "hoge@gmail.address")
      (a-token (org-gcal--get-access-token)))
 (deferred:$
   (request-deferred
    (format org-gcal-events-url some-gmail-address)
    :type "GET"
    :params `((access_token . ,a-token)
              (key . ,org-gcal-client-secret)
              (singleEvents . "True")
              (timeMin . ,(org-gcal--subsract-time))
              (timeMax . ,(org-gcal--add-time))
              ("grant_type" . "authorization_code"))
    :parser 'org-gcal--json-read
    :error
    (function* (lambda (&key error-thrown &allow-other-keys&rest _)
                 (message "Got error: %S" error-thrown))))
   (deferred:nextc it
     (lambda (response)
       (message "status %S" (request-response-status-code response))
       (message "status %d" (request-response-status-code response))))))
```

Above code is executed without network, I get

```
status nil
deferred error : (error "Format specifier doesn't match argument type")
```
Please check it.