Pré signup de users

[joaopcm]

Is your feature request related to a problem? Please describe.
Dar erro caso o e-mail já esteja cadastrado na base dados assim que o usuário preencher o input no app.

Describe the solution you'd like
A clear and concise description of what you want to happen.

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context
Add any other context or screenshots about the feature request here.