Attachment_fu : Possible to delete record if no file present?

I'm using Attachment fu to allow file attachments to my TimeOff model
(for an employee program). An attachment is only optional for the
app, so some TimeOffs will have files attached and some won't.

The problem is I can't delete a TimeOff if there is no file present.
However, it does delete fine if there is a file.

Here is my controller destroy action:

  def destroy
    @time_off = TimeOff.find(params[:id])
    id = @time_off.employee_id

    @time_off.destroy
    redirect_to :action => 'list', :id => id
  end

Here is my error:

TypeError in Time offsController#destroy

can't convert nil into String

RAILS_ROOT: script/../config/..
Application Trace | Framework Trace | Full Trace

vendor/plugins/attachment_fu/lib/technoweenie/attachment_fu/backends/
file_system_backend.rb:21:in `join'
vendor/plugins/attachment_fu/lib/technoweenie/attachment_fu/backends/
file_system_backend.rb:21:in `full_filename'
vendor/plugins/attachment_fu/lib/technoweenie/attachment_fu/backends/
file_system_backend.rb:63:in `destroy_file'
/usr/local/lib/ruby/gems/1.8/gems/activerecord-1.15.3/lib/
active_record/callbacks.rb:333:in `send'
/usr/local/lib/ruby/gems/1.8/gems/activerecord-1.15.3/lib/
active_record/callbacks.rb:333:in `callback'
/usr/local/lib/ruby/gems/1.8/gems/activerecord-1.15.3/lib/
active_record/callbacks.rb:330:in `each'
/usr/local/lib/ruby/gems/1.8/gems/activerecord-1.15.3/lib/
active_record/callbacks.rb:330:in `callback'
/usr/local/lib/ruby/gems/1.8/gems/activerecord-1.15.3/lib/
active_record/callbacks.rb:322:in `destroy_without_transactions'
/usr/local/lib/ruby/gems/1.8/gems/activerecord-1.15.3/lib/
active_record/transactions.rb:125:in `destroy'
/usr/local/lib/ruby/gems/1.8/gems/activerecord-1.15.3/lib/
active_record/connection_adapters/abstract/database_statements.rb:
59:in `transaction'
/usr/local/lib/ruby/gems/1.8/gems/activerecord-1.15.3/lib/
active_record/transactions.rb:95:in `transaction'
/usr/local/lib/ruby/gems/1.8/gems/activerecord-1.15.3/lib/
active_record/transactions.rb:121:in `transaction'
/usr/local/lib/ruby/gems/1.8/gems/activerecord-1.15.3/lib/
active_record/transactions.rb:125:in `destroy'
app/controllers/time_offs_controller.rb:52:in `destroy'

I have the same problem, and I've not been able to figure out a good
solution yet. Anyone know?

Thanks!

I ended up splitting attachments into their own model, which also
allows multiple attachments per TimeOff, if needed. The implementation
of the form is a little tricky, having to create 2 models in one form,
but a tutorial on Railscasts.com helped bunches.

Oh, and I added this to my Timeoff model so when I delete a TimeOff,
it deletes all files too:

  has_many :attachments, :dependent => :destroy