`.to_sql` does not work with joined paranoia model: Undefined method 'relation' for Arel::Nodes::BindParam

[Laykou]

1. .to_sql method works without acts_as_paranoid
2. Calling the .to_sql on the User model without joins works as well:

> User.all.to_s
=> "SELECT \"users\".* FROM \"users\" WHERE \"users\".\"deleted_at\" IS NULL" 

3. But calling .to_sql with joins on the paranoia model throws:

NoMethodError (undefined method 'relation' for #<Arel::Nodes::BindParam:0x00007f91ece6e120>)

How to reproduce:

class User < ApplicationRecord
  acts_as_paranoid
end

class UserSetting < ApplicationRecord
  belongs_to :user
end

UserSetting.joins(:user).to_sql

# NoMethodError (undefined method 'relation' for #<Arel::Nodes::BindParam:0x00007f91ece6e120>)