Firebase authenticating with wrong email or password displays strange error

You most likely need to set up error handling. Something like this...

login() {
    this.af.auth.login({
        email: this.email,
        password: this.password,
    },
    {
        provider: AuthProviders.Password,
        method: AuthMethods.Password,
    }).catch(function(error) {
        var errorMessage = error.message
        alert(errorMessage)
    })
}

You have to handle the response when the password is wrong. I'm not sure about the AngularFire way. I personally couldn't find it. I relied on the Firebase documentation to do this, which is linked in the AngularFire docs.