I'm getting a NoMethodError and I'm not sure why

I'm creating a join table that will show me which employee sold which comic. When I type in my employee name It is giving me this error

NoMethodError in Showemployeesales#employeesaleout
undefined method `name_id' for nil:NilClass

Here is my code for my controller

 def employeesaleout
 @employee_name = params[:employee_name_in]
 r = Employee.find_by_name_id(@employee_name)
 @sale_list = r.sales
end

Here is my code for my input view "employeenamein"

   <h1>Showemployeesales#employeenamein</h1>
   <p>Find me in app/views/showemployeesales/employeenamein.html.erb</p>
    <%= form_tag(showemployeesales_employeesaleout_path, :controller => 
    "showemployeesales", :action => "employeesaleout", :method => "post") do 
      %>

    <div class="field">
      <%= label_tag :Employee_Name %><br />
        <%= text_field_tag :employee_name_in %>
    </div>

    <div class="actions">
          <%= submit_tag "Submit Employee Name" %>
    </div>
    <% end %>

Here is my code for my output view

    <center><h1>These are the Sales for <%= @employee_name %> </h1></center>
    <br /> <br />

     <center><table width = 65% border = 1> 
     <tr> <th> Comic Name </th><th> Comic ID </th></tr>   
     <% @sale_list.each do |m| %>     

     <tr> <td> <%= m.product.name_id %> </td> <td> <%= m.product.id_no %> 
     </td></tr>
     <% end %> </table> </center><br /> <br />

And my products table under my schema

   create_table "products", force: :cascade do |t|
   t.string   "name_id"
   t.integer  "id_no"
   t.datetime "created_at", null: false
   t.datetime "updated_at", null: false
   end

What am I doing wrong?