Rails アソシエーションでのエラー

前提・実現したいこと

railsの勉強を始めたばかりで、入門書の見本を見ながらコードを打ち込んでいます。
アソシエーションの項目で行き詰まり、どこが間違えているのかがわかりません。

発生している問題・エラーメッセージ

ActionView::Template::Error (undefined method `name' for nil:NilClass):
     9:     <tr>
    10:         <td><%= obj.id %></td>
    11:         <td><a href = "/messages/<%= obj.id %>"><%= obj.title %></a></td>
    12:         <td><%= obj.person.name %></td>
    13:         <td><a href = "/messages/edit/<%= obj.id %>">Edit</a><td>
    14:         <td><a href = "javascript:delData(<%= obj.id %>);">Delete</a></td>
    15:     </tr>

app/views/messages/index.html.erb:12
app/views/messages/index.html.erb:8

該当のソースコード

app//views/messages/index.html.erb

<h1 class = "display-4 text-primary">
    Message#index</h1>
<p><%= @msg %></p>
<table class = "table">
    <tr>
        <th>Id</th><th>title</th><th>person</th><th colspan = "2"></th>
    </tr>
    <% @data.each do |obj| %>
    <tr>
        <td><%= obj.id %></td>
        <td><a href = "/messages/<%= obj.id %>"><%= obj.title %></a></td>
        <td><%= obj.person.name %></td>
        <td><a href = "/messages/edit/<%= obj.id %>">Edit</a><td>
        <td><a href = "javascript:delData(<%= obj.id %>);">Delete</a></td>
    </tr>
    <% end %>
</table>
<script>
function delData(num){
    if (confirm('このデータを削除しますか?')){
        document.location = "/messages/delete/" + num;
    }
    return false;
}
</script>

app/models/message.rb

class Message < ApplicationRecord
    belongs_to :person
    
    validates :message, presence: {message: "を書いてください。"}
end

app/views/people/show.html.erb

<h1 class = "display-4 taxt-primary">People#show</h1>
<p><%= @msg %></p>
<table class = "table">
    <tr><th>Id</th>
    <td><%= @data.id %></td></tr>
    <tr><th>Name</th>
    <td><%= @data.name %></td></tr>
    <tr><th>Age</th>
    <td><%= @data.age %></td></tr>
    <tr><th>Mail</th>
    <td><%= @data.mail %></td></tr>
    <tr><th>Maessage</th>
    <td>
        <% if @data.message != nil then %>
            <% @data.message.each do |obj| %>
                <%= "「" + obj.title + "」" %>
            <% end %>
        <% end %>
        </td></tr>
</table>

app/controllers/messages_controller.rb

class MessagesController < ApplicationController
  layout "messages"

  def index
    @msg = "Massage data."
    @data = Message.all
  end

  def show
    @msg = "Indexed data."
    @message = Message.find(params[:id])
  end

  def add
    @msg = "Massege data."
    @message = Message.new
  end

  def create
    @message = Message.new message_params
    if @message.save then
      redirect_to "/messages"
    else
      render "add"
    end
  end

  def edit
    @msg = "edit data.[id = " + params[:id] + "]"
    @message = Message.find(params[:id])
  end

  def update
    obj = Message.find(params[:id])
    obj.update(message_params)
    redirect_to "/messages"
  end

  def delete
    obj = Message.find(params[:id])
    obj.destroy
    redirect_to "/messages"
  end

  private
  def message_params
    params.require(:message).permit(:person_id, :title, :message)
  end
  
end