ransack_alias doesn't work in associations

[matgaw]

class Parent
  ransack_alias :full_name, :first_name_or_last_name
end

class Child
  belongs_to :parent
end

Working scenario:

Parent.ransack(full_name_cont: 'a').result # works correctly

Error scenario:
Child.ransack(parent_full_name_cont: 'a').result
Result:

undefined method `type' for nil:NilClass (NoMethodError)

      attr.klass.columns.find { |column| column.name == name }.type
                                                              ^^^^^