TypeError: Cannot create property 'mailer' on string 'host' Nest JS Service with Injectable

[theofrgs]

Hello, I try to create a nest js service to use mailer API, when I try to build my service I've got this error: TypeError: Cannot create property 'mailer' on string 'host'

` private mailjet: Client;

constructor() {
    this.mailjet = new Client({
        apiKey: "",
        apiSecret: "",
    });
}

`

[theofrgs]

Error from my side