Can't view the errors in the browser on a Ruby on Rails form

I am using rails 7.3 I am trying to see the errors in the browser when a prodcut can't be created. I am working on an aplicattion that has a restaurant, category and a product models.

The associations are as follows:

Product belongs_to :restaurant

Product belongs_to :category

Restaurant has_many :products

Restaurant has_many :categories

Category has_many :products

Category belongs_to :restaurant

I have a form that creates/edits a product and it allows me to create a Category on the fly if needed. This is the form.

<div class="card-body rounded">
  <%= form_with(model: [@restaurant, @product]) do |form| %>
    <p class="red"><i><b>Note: </b>Labels with (<b> ** </b>) are madatory </i></p>
    <% if @product.errors.any? %>
      <div id="error_explanation">
        <h2><%= pluralize(@product.errors.count, "error") %> prohibited this product from being saved:</h2>
        <ul>
          <% @product.errors.full_messages.each do |message| %>
            <li><%= message %></li>
          <% end %>
        </ul>
      </div>
    <% end %>
    <%= form.hidden_field :restaurant_id, value: @restaurant.id %>
    <!--- FROM HERE THE FORM --->
    <div class="row mb-4">
      <div class="col-sm-5  align-right label">
        <%= form.label :name, '** Product Name' %>
      </div>
      <div class="col-sm-7 form-input">
        <%= form.text_field :name, id: "product_name", placeholder: "Enter name", oninput: "checkInput()" %>
      </div>
    </div>
    <div class="text-center mb-4 red">
      <p><i>You can either <b> Select</b> or Create a <b> New Category </b>. You can not use both. </i> </p>
    </div>
    <div class="row mt-3 mb-3">
      <div class="col-sm-5 align-right label">
        <%= form.label :Category, "** Select Category" %>
      </div>
      <div class="col-sm-7 form-input">
        <%= form.collection_select :category_id, @restaurant.categories, :id, :name, { prompt: 'Select existing category' }, { class: "collection-select", id: "product_category_id" , oninput: "checkInput()"}  %>
      </div>
    </div>
    <div class="text-center mb-3">
      <b> -- OR -- </b>
    </div>
    <div class="row mb-4">
      <div class="col-sm-5 align-right label">
        <%= form.label :new_category_name, "** Create a New Category:" , class: 'label' %>
      </div>
      <div class="col-sm-7 form-input">
        <%= form.text_field :new_category_name, placeholder: "Enter New Category", oninput:"checkInput()" %>
      </div>
    </div>
    <% if product.created_at != product.updated_at %>
      <div class ="row mb-4">
        <div class="col-sm-5 align-right label">
          <%= form.label :updated_by, 'Modified by Form',  id:"product_updated_by"  %>
        </div>
        <div class="col-sm-7 form-input">
          <%= user_updated_identifier(product) %>
        </div>
      </div>
      <div class ="row mb-4">
        <div class="col-sm-5 align-right label">
          <%= form.label :updated_at, 'Modified on',  id:"product_updated_at"  %>
        </div>
        <div class="col-sm-7 form-input">
          <%= product.updated_at.strftime("%d-%b-%Y @ %H:%M")  %>
        </div>
      </div>
    <% end %>
    <div class="mt-5 mb-5 text-center">
      <% if action_name == 'edit' %>
        <%= form.submit 'Update Product', class: 'btn btn-submit', id:"myButton" %>
      <% else %>
        <%= form.submit class: 'btn btn-submit', id:"myButton" %>
      <% end %>
    <% end %>
  </div>
</div>

It looks as follows in the browser

The new and create actions in the products_controller are as follows:

  def new
    @product = @restaurant.products.new
    @categories = @restaurant.categories
  end


  def create
    @product = @restaurant.products.new(product_params)
  
    if @product.new_category_name.present?
      new_category = @restaurant.categories.find_or_create_by(name: @product.new_category_name)
      @product.category_id = new_category.id
    end
    
    @product.created_by = current_user.id
    puts "Product params AAAAA: #{product_params}"
  
    if @product.save
      redirect_to restaurant_products_path(@restaurant), notice: "Product was successfully created."
    else
      puts @product.errors.full_messages
      render :new
    end
  end

When I try to create the product without a name or a category I get the following error in the terminal:

14:52:45 web.1 | Category must exist

14:52:45 web.1 | Name can't be blank

14:52:45 web.1 | Category can't be blank

Which indicates that the else stament in the create action is being executed and the puts ( puts @product.errors.full_messages) is being executed. If the information is correct in the terminal why I can't see the errors in the view (browser)?

I have tried to sort it by myself but if has been a task of a day and counting...