Rails 5 throw abort : how do I setup error messages?

Rails has introduced this throw(:abort) syntax, but now how do I get meaningful destroy errors ?

For validation errors one would do

if not user.save
  # => user.errors has information

if not user.destroy
  # => user.errors is empty

Here is my model

class User

  before_destroy :destroy_validation,
    if: :some_reason

  private

  def destroy_validation
    throw(:abort) if some_condition
  end

You can use errors.add for your class method.

User model:

def destroy_validation
  if some_condition
    errors.add(:base, "can't be destroyed cause x,y or z")
    throw(:abort)
  end
end

Users controller:

def destroy
  if @user.destroy
    respond_to do |format|
      format.html { redirect_to users_path, notice: ':)' }
      format.json { head :no_content }
    end
  else
    respond_to do |format|
      format.html { redirect_to users_path, alert: ":( #{@user.errors[:base]}"}
    end
  end
end