railsで複数画像投稿を実装したら画像無しの投稿を編集できなくなった

https://qiita.com/gakinchoy7/items/ac1d8e64e33c3ddd377b
https://qiita.com/0thefool/items/5af0f17f0075e7e0e013

上記のサイトを参考にして複数画像投稿機能を実装しました。
投稿自体は画像アリでもなしでも可能ですが
画像のない投稿に編集で画像を追加するとparamsは送られているのにnilが入ってしまいます。
解決法がわかる方は教えてください(__)。お願いします

Started PATCH "/posts/16" for ::1 at 2021-04-03 22:12:14 +0900
Processing by PostsController#update as HTML
  Parameters: {"authenticity_token"=>"[FILTERED]", "post"=>{"content"=>"こんにちわ", "images_attributes"=>{"0"=>{"image"=>"453789.jpg"}, "1"=>{"image"=>""}, "2"=>{"image"=>""}, "3"=>{"image"=>""}, "4"=>{"image"=>""}}, "tag_ids"=>"rails ruby"}, "commit"=>"投稿", "id"=>"16"}
  Post Load (0.1ms)  SELECT "posts".* FROM "posts" WHERE "posts"."id" = 
$1 LIMIT $2  [["id", 16], ["LIMIT", 1]]
  ↳ app/controllers/posts_controller.rb:79:in `set_post'
  User Load (0.1ms)  SELECT "users".* FROM "users" WHERE "users"."id" = 
$1 ORDER BY "users"."id" ASC LIMIT $2  [["id", 1], ["LIMIT", 1]]        
  TRANSACTION (0.1ms)  BEGIN
  ↳ app/controllers/posts_controller.rb:53:in `update'
  User Load (0.1ms)  SELECT "users".* FROM "users" WHERE "users"."id" = 
$1 LIMIT $2  [["id", 1], ["LIMIT", 1]]
  ↳ app/controllers/posts_controller.rb:53:in `update'
  Image Create (0.8ms)  INSERT INTO "images" ("post_id", "image", "created_at", "updated_at") VALUES ($1, $2, $3, $4) RETURNING "id"  [["post_id", 16], ["image", nil], ["created_at", "2021-04-03 13:12:14.156140"], ["updated_at", "2021-04-03 13:12:14.156140"]]
  ↳ app/controllers/posts_controller.rb:53:in `update'
  Image Create (0.1ms)  INSERT INTO "images" ("post_id", "created_at", "updated_at") VALUES ($1, $2, $3) RETURNING "id"  [["post_id", 16], ["created_at", "2021-04-03 13:12:14.158176"], ["updated_at", "2021-04-03 13:12:14.158176"]]
  ↳ app/controllers/posts_controller.rb:53:in `update'
  Image Create (0.1ms)  INSERT INTO "images" ("post_id", "created_at", "updated_at") VALUES ($1, $2, $3) RETURNING "id"  [["post_id", 16], ["created_at", "2021-04-03 13:12:14.159287"], ["updated_at", "2021-04-03 13:12:14.159287"]]
  ↳ app/controllers/posts_controller.rb:53:in `update'
  Image Create (0.3ms)  INSERT INTO "images" ("post_id", "created_at", "updated_at") VALUES ($1, $2, $3) RETURNING "id"  [["post_id", 16], ["created_at", "2021-04-03 13:12:14.166773"], ["updated_at", "2021-04-03 13:12:14.166773"]]
  ↳ app/controllers/posts_controller.rb:53:in `update'
  Image Create (0.2ms)  INSERT INTO "images" ("post_id", "created_at", "updated_at") VALUES ($1, $2, $3) RETURNING "id"  [["post_id", 16], ["created_at", "2021-04-03 13:12:14.168800"], ["updated_at", "2021-04-03 13:12:14.168800"]]
  ↳ app/controllers/posts_controller.rb:53:in `update'
  TRANSACTION (0.9ms)  COMMIT
  ↳ app/controllers/posts_controller.rb:53:in `update'
Redirected to http://localhost:3000/dashboard
Completed 302 Found in 25ms (ActiveRecord: 3.0ms | Allocations: 13196)

edit
1      p 最大5枚までアップロードできます
2      .post__drop__box__container
3        .prev-content
4    
5          //JSで挿入したhtmlと同じ形 each文でのプレビュー表示
6          - @post.images.each_with_index do |image,i|
7              .preview-box
8                .upper-box
9                  = image_tag image.image.to_s, width: "112", height: "112", alt: "preview"
10                .lower-box
11                  .update-box
12                    .edit-btn 編集
13                  .delete-box
14                    div class="delete-btn" data-delete-id="#{i}" 削除
15        .label-content
16          = f.label :"images_attributes_#{@post.images.length}_image", class: "label-box" do
17            <i class="fas fa-camera"></i>
18
19        .hidden-content
20          = f.fields_for :images do |i|
21    
22            //プレビューが出ている分のfile_fieldとdelete用のチェックボックスを設置
23            = i.file_field :image,class:"hidden-field"
24            = i.check_box:_destroy,class:"hidden-field"
25    
26            //5つのfile_fieldを準備するに当たって、足りない分を表示
27          - @post.images.length.upto(4) do |i|
28            input name="post[images_attributes][#{i}][image]" id="post_images_attributes_#{i}_image" class="hidden-field" type="file"
29