c2c_correct_invoice, modify action => error if invoice without payment date

In the module c2c_correct_invoice, when we try to refund an invoice with the "modify action", the following error appears when an invoice is without payment term and date :

  File "/usr/lib/python2.5/site-packages/tinyerp-server/addons/c2c_correct_invoice/c2c_wizard_refund.py", line 34, in _invoice_modify
    return self._compute_refund(cr, uid, data, 'modify', context)
  File "/usr/lib/python2.5/site-packages/tinyerp-server/addons/c2c_correct_invoice/c2c_wizard_refund.py", line 170, in _compute_refund
    inv.write(cr, uid, [inv_id],data['value'])
KeyError: 'value'

The code of c2c_correct_invoice/c2c_wizard_refund could be corrected like that if I'm not wrong :

158 inv.write(cr, uid, [inv_id],data['value'])

with

158 if data:
159 inv.write(cr, uid, [inv_id],data['value'])