ActiveRecord::AssociationTypeMismatch in Devise::RegistrationsController#create

Question

cloud9でwebアプリケーションを作っているのですが、deviseで新規登録した時にActiveRecord::AssociationTypeMismatch in Devise::RegistrationsController#create
のエラーが発生します。いまいちこのエラーの意味がわからずどこをどう改善すれば良いかわかりません。
ネットで調べてみても良い情報が見つからず困っています。

仕様
・ログイン機能はdeviseを使っています。
・アソシエーションを使っています。

routes.rb

Rails.application.routes.draw do
  devise_for :customers
  devise_for :admins
  namespace :public do
    get 'sign_in' => 'sessions#new'
    get 'sign_up' => 'registrations#new'
    resources :items,only:[:index,:show,:create]
    resources :homes,only:[:index]
    resources :cart_items,only:[:show,:create,:update,:index,:destroy]
    delete '/cart_items/destroy_all' => 'cart_items#destroy_all', as:'cart_items_destroy_all'
    resources :orders,only:[:new,:create]
  end
  namespace :admin do
    get  'sign_in' => 'sessions#new'
    resources :items, only: [:create, :index, :show, :edit, :update, :destroy,:new]
    resources :genres, only: [:index, :create,:edit, :update]
    resources :customers, only: [:index, :create, :new, :update, :destroy, :show]
  end
  root  'admin/items#top'
  get 'about' =>'admin/items#about'
end

application.html.erb

lass ApplicationController < ActionController::Base
  before_action :configure_permitted_parameters, if: :devise_controller?

  protected


  def after_sign_out_path_for(resource)
   root_path
  end


  def after_sign_in_path_for(resource)
    case resource
    when Admin
      admin_root_path(resource)
    when Customer
     public_items_path(resource)
    end
  end

  def configure_permitted_parameters
    devise_parameter_sanitizer.permit(:sign_up, keys: [:name,:email,:first_name,:last_name_kana,:first_name_kana,:address,:postal_code,:email,:telephone_number,:is_deleted])
  end
end

new.html.erb

<div class="container">
   <div class="row">
     <div class="col  mx-auto w-75">
       <div class="customer-title">
        <h4 class="bg-light text-center m-4" style="width:20%;">新規会員登録</h4>
       </div>
        <%= form_for (@customer),url:  customer_registration_path  do |f| %>
          <%= render "devise/shared/error_messages", resource: resource %>
            <div class="customer-list d-flex">
              <div class="customer-left">
                <div class="customer-item">
                  <p>名前</p>
                  <p>フリガナ</p>
                  <p>メールアドレス</p>
                  <p>郵便便番号(ハイフンなし)</p>
                  <p>住所</p>
                  <p>電話番号(ハイフンなし)</p>
                  <p>パスワード(6文字以上)</p>
                  <p>パスワード(確認用)</p>
                </div>
              </div>
                <div class="customer-right pl-4">
                  <div class="customer-name d-flex p-1">
                    (姓)　<%= f.text_field :last_name %>
                    (名)　<%= f.text_field :first_name %>
                  </div>
                    <div class="customer-name2 d-flex p-1">
                      (セイ) <%= f.text_field :last_name_kana %>
                      (メイ) <%= f.text_field :first_name_kana %>
                    </div>
                  <div class="customer-email p-1">
                    <%= f.email_field :email, autofocus: true, autocomplete: "email" %>
                  </div>
                    <div class="customer-postal_code p-1">
                      <%= f.text_field :postal_code %>
                    </div>
                      <div class="customer-street-address p-1">
                        <%= f.text_field :address %>
                      </div>
                        <div class="customer-phone p-1">
                          <%= f.telephone_field :telephone_number %>
                        </div>
                          <div class="customer-password p-1">
                            <% if @minimum_password_length %>
                            <% end %>
                            <%= f.password_field :password, autocomplete: "new-password" %>
                          </div>
                            <div class="customer-password2 p-1">
                              <%= f.password_field :password_confirmation, autocomplete: "new-password" %>
                            </div>
                              <div class="actions mt-3">
                                <%= f.submit "新規登録",:class=>"bg-success text-white border border-light",:style=>"padding-right:50px; padding-left:50px;" %>
                              </div>
                  </div>
              </div>
            <% end %>
              <div class="customer-login">
                <h4 class="bg-light w-25 m-4  text-center">既に登録済みの方</h4>
                <p class="m-2"><%= link_to "こちら", new_customer_session_path,:class=>"m-2" %> からログインしてください</p>
              </div>
  </div>
</div>

customer.rb

class Customer < ApplicationRecord
  # Include default devise modules. Others available are:
  # :confirmable, :lockable, :timeoutable, :trackable and :omniauthable
  devise :database_authenticatable, :registerable,
         :recoverable, :rememberable, :validatable
  has_many :cart_items, dependent: :destroy
  has_many :orders, dependent: :destroy
  belongs_to :address,optional: true
end