name no estaba indexado!

db/migrate/20220314201955_add_serial_number_to_raspberry.rb

@@ -4,15 +4,11 @@
 class AddSerialNumberToRaspberry < ActiveRecord::Migration[6.1]
   def up
     add_column :raspberries, :serial_number, :string
-
-    remove_index :raspberries, :name
     add_index :raspberries, :serial_number, unique: true
   end
 
   def down
     remove_index :raspberries, :serial_number
-    add_index :raspberries, :name, unique: true
-
     remove_column :raspberries, :serial_number
   end
 end