active record query issue: Joins from a default_scope

begin
  require "bundler/inline"
rescue LoadError => e
  $stderr.puts "Bundler version 1.10 or later is required. Please update your Bundler"
  raise e
end

gemfile(true) do
  source "https://rubygems.org"
  # Activate the gem you are reporting the issue against.
  gem "activerecord", "5.0.0.1"
  gem "sqlite3"
end

require "active_record"
require "minitest/autorun"
require "logger"

# Ensure backward compatibility with Minitest 4
Minitest::Test = MiniTest::Unit::TestCase unless defined?(Minitest::Test)

# This connection will do for database-independent bug reports.
ActiveRecord::Base.establish_connection(adapter: "sqlite3", database: ":memory:")
ActiveRecord::Base.logger = Logger.new(STDOUT)

ActiveRecord::Schema.define do

  create_table :events, force: true do |t|
    t.string :name
    t.timestamps
  end

  create_table :appointments, force: true do |t|
    t.references :event
    t.string :name
    t.timestamps
  end

  create_table :transaction_charges, force: true do |t|
    t.references :appointment
    t.boolean :status
    t.string :name
    t.timestamps
  end

  create_table :seats, force: true do |t|
    t.references :appointment
    t.string :name
    t.timestamps
  end
end

class Event < ActiveRecord::Base
  has_many :appointments, inverse_of: :event
  has_many :seats, -> { joins(' INNER JOIN `transaction_charges` ON `transaction_charges`.`appointment_id` = `appointments`.`id` ') }, through: :appointments
  has_many :synonym_seats, through: :appointments, source: :seats
end

class Appointment < ActiveRecord::Base
  has_one :transaction_charge, inverse_of: :appointment
  has_many :seats, inverse_of: :appointment
  belongs_to :event, inverse_of: :appointments

  accepts_nested_attributes_for :transaction_charge

  default_scope { joins(:transaction_charge).where(['transaction_charges.status =? ', true]) }
end

class TransactionCharge < ActiveRecord::Base
  belongs_to :appointment, inverse_of: :transaction_charge
end

class Seat < ActiveRecord::Base
  belongs_to :appointment, inverse_of: :seats
end


class BugTest < Minitest::Test
  def test_association_stuff
    event = Event.create(name: 'Test event')
    a = event.appointments.create(name: 'appointment 01', transaction_charge_attributes: {status: true, name: 'transaction_charge 01'})
    a.seats.create(name: 'A1')
    a.seats.create(name: 'A2')
    a.seats.create(name: 'B1')
    a.seats.create(name: 'B2')
    a.seats.create(name: 'C9')


    assert_equal 1, event.appointments.count
    assert_equal 5, event.seats.count
    assert_raises(ActiveRecord::StatementInvalid) {
      event.synonym_seats.count
    }
  end
end