Non-follows allowed in lists

app/models/list_account.rb

@@ -12,7 +12,7 @@
 class ListAccount < ApplicationRecord
   belongs_to :list
   belongs_to :account
-  belongs_to :follow
+  belongs_to :follow, optional: true
 
   validates :account_id, uniqueness: { scope: :list_id }
 
@@ -21,6 +21,6 @@ class ListAccount < ApplicationRecord
   private
 
   def set_follow
-    self.follow = Follow.find_by(account_id: list.account_id, target_account_id: account.id)
+    self.follow = Follow.find_by!(account_id: list.account_id, target_account_id: account.id) unless list.account_id == account.id
   end
 end

db/migrate/20200430154012_change_list_account_follow_nullable.rb

@@ -0,0 +1,5 @@
+class ChangeListAccountFollowNullable < ActiveRecord::Migration[5.2]
+  def change
+    change_column_null :list_accounts, :follow_id, true
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 2020_04_20_223346) do
+ActiveRecord::Schema.define(version: 2020_04_30_154012) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"