Template missing when two validations fail

gistfile1.txt

Template is missing
Missing template registrants/index, application/index with {:locale=>[:en], :formats=>[:html], :variants=>[], :handlers=>[:erb, :builder, :raw, :ruby, :coffee, :arb, :jbuilder]}. Searched in: * "/home/ubuntu/workspace/backend-dev-test-devkinetic/app/views" * "/usr/local/rvm/gems/ruby-2.2.2/gems/html5-rails-0.1.0/app/views" * "/usr/local/rvm/gems/ruby-2.2.2/gems/devise-3.4.1/app/views" * "/usr/local/rvm/gems/ruby-2.2.2/bundler/gems/activeadmin-8968efcc51cc/app/views" * "/usr/local/rvm/gems/ruby-2.2.2/gems/kaminari-0.16.3/app/views"
Extracted source (around line #46):

    def find(*args)
      find_all(*args).first || raise(MissingTemplate.new(self, *args))
    end

    def find_all(path, prefixes = [], *args)

Rails.root: /home/ubuntu/workspace/backend-dev-test-devkinetic

home_controller.rb

class HomeController < ApplicationController
  def index
    @registrant = Registrant.new # make an instance of Registrant availiable to the form
  end

  def thanks
  end
end

registrant.rb

class EmailValidator < ActiveModel::EachValidator
  def validate_each(record, attribute, value)
    unless value =~ /\A([^@\s]+)@((?:[-a-z0-9]+\.)+[a-z]{2,})\z/i
      record.errors[attribute] << (options[:message] || "is not an email")
    end
  end
end

class Registrant < ActiveRecord::Base
  # We'll need some validations here to make sure the user fills out the form correctly
  validates :fname, presence: true
  validates :lname, presence: true
  validates :cname, presence: true
  validates :email, presence: true, uniqueness: true, email: true
  validates :title, presence: true
  validates :mobile_phone, presence: true, numericality: true, length: { minimum: 10, maximum: 15 }
  # Make sure they choose at least one of the events to attend
  validate :one_event_checked

  def one_event_checked
    unless welcome_reception || smart_choice_reception
      errors.add(:selection, "test")
    end
  end
end

registrant_controller.rb

class RegistrantsController < ApplicationController
  
  def index
    @registrant = Registrant.new # fire off the create action
    render 'home/index'
  end
  
  def create
    @registrant = Registrant.new(registrant_params)
    
    if @registrant.save # did the record pass validadtion?
      redirect_to thank_you_path
    else
      render 'home/index'
    end
      
  end
  
  private
  
  def registrant_params # only accept values from the form
    params.require(:registrant).permit(:fname, :lname, :cname, :email, :title, :mobile_phone, :welcome_reception, :smart_choice_reception)
  end
  
end