'Try to fix last field when we know current field set size.
Returns new added field if any, or None.'

def _fixLastField(self):

    assert (self._size is not None)
    message = ['stop    parser']
    self._field_generator = None
    while (self._size < self._current_size):
        field = self._deleteField((len(self._fields) - 1))
        message.append(('delete    field    %s' % field.path))
    assert (self._current_size <= self._size)
    size = (self._size - self._current_size)
    if size:
        field = createRawField(self, size, 'raw[]')
        message.append('add    padding')
        self._current_size += field.size
        self._fields.append(field._name, field)
    else:
        field = None
    message = ',    '.join(message)
    self.warning(('[Autofix]    Fix    parser    error:    ' + message))
    assert (self._current_size == self._size)
    return field
