Can't send a message

[macabeus]

Thank you for this package. I'm trying to use it in order to send a notification for mobile app using Firebase, but I can't.
When I try to send a message I'm always receiving this error:

[error] #PID<0.727.0> running BckoWeb.Endpoint (connection #PID<0.725.0>, stream id 2) terminated
Server: localhost:4003 (http)
Request: GET /api/v1/news/1/push
** (exit) an exception was raised:
    ** (MatchError) no match of right hand side value: :error
        (firebase_admin_ex 0.1.0) lib/messaging.ex:17: FirebaseAdminEx.Messaging.send/2

I created a new account on Google Cloud Platform, I downloaded its json and set the path on GOOGLE_APPLICATION_CREDENTIALS. So I don't know why I'm receiving this error on Goth.Config.get(client_email, :project_id) line.

How to solve that?