nested resource errors

invites_controller.rb

class InvitesController < ApplicationController
  def create
    @project = Project.find(params[:project_id])
    @invite = @project.invites.build(params[:invite])
    
    if @project.save
      redirect_to project_url(@project), :notice => 'Success message.'
    else
      render # ?? project/show ??
    end
  end
end

show.html.erb

<!-- Details of @project rendered up here -->

<!-- Render errors for failed @invite here --> 

<%= form_for([@project, @invite]) do |f| %>

<p>
  <%= f.label :email %><br>
  <%= f.text_field :email %>
</p>

<p>
  <%= f.submit %>
</p>
<% end %>