メッセージが一度しか送れない

sendボタンを押すとメッセージは非同期で表示され、データベースにも残るが
リロードしないともう一度メッセージは送れず、
リロードするとメッセージデータが消える

検証ツールを使ったら以下のエラーが見受けられました

Uncaught TypeError: Cannot read property 'insertAdjacentHTML' of null
at Subscription.received (message_channel.js:16)
at action_cable.js:536
at Array.map (<anonymous>)
at Subscriptions.notify (action_cable.js:535)
at Connection.message (action_cable.js:369)

actioncable使ってます

message_channel.js

ここの messages.insertAdjacentHTML('afterbegin', html);
部分でエラー

import consumer from "./consumer"

consumer.subscriptions.create("MessageChannel", {
  connected() {
    // Called when the subscription is ready for use on the server
  },

  disconnected() {
    // Called when the subscription has been terminated by the server
  },

  received(data) {
    const html = `<p>${data.js_content.text}</p>`;
    const messages = document.getElementById('messages');
    const newMessage = document.getElementById('message_text');
    messages.insertAdjacentHTML('afterbegin', html);
    newMessage.value='';
    // Called when there's incoming data on the websocket for this channel
  }
});

　　messages controller

class MessagesController < ApplicationController
  def new
    @book = Book.find(params[:book_id])
    @messages = Message.all
    @message = Message.new
  
  end

  def create
    @book = Book.find(params[:book_id])
    @message = @book.build_message(message_params)
    if @message.save!
    ActionCable.server.broadcast 'message_channel', js_content: @message
    # redirect_to "/books/#{@book.id}/messages/new"
    end
  end

  private 
 def message_params
  params.require(:message).permit(:text).merge(user_id: current_user.id)
 end
end

メッセージのやり取りを行う場所　message new.html.erb

h1 class = "top-messsage"><%="#{@book.name}"%></h1>

  <% @messages.reverse_each do |message| %>
  <div class = "message-head">
   <div id='messages'>
    <i><%= message.text %></i>
   
       <%= message.user.nickname%>
  </div>
   <% end %>
</div>
  <div class="box-new">
    <%= form_with model: @message, url: book_messages_path,local: true do |f| %>
     <%= f.text_field :text, id: "message_text" %>
     <%= f.submit '送信' %>
    <% end %>
     <div class="message-new">
   <i class="container2">  <%= link_to 'home', "/", class: "btn-open3" %></i>
   </div>
  </div>