Cannot read property 'then' of undefined

[AlexVFornazieri]

Hey guys,

I try do it works in my app, but when I call dispatch().then() in a vue component this erro "Cannot read property 'then' of undefined" is showed, any tip?

this.$store.dispatch('signInWithEmail', {
        email: this.formEmail,
        password: this.formPassword
      }).then(() => {
        this.loading = false
     })

Thanks all