Fail with a more explicit error when field name does not exist
Record.__getitem__ returns False if the name does not exist. This generates confusing exception later [1].
[1] https://groups.google.com/d/msg/tryton/DvF3SFwfrqE/Q-bVSs0KAwAJ
Record.__getitem__ returns False if the name does not exist. This generates confusing exception later [1].
[1] https://groups.google.com/d/msg/tryton/DvF3SFwfrqE/Q-bVSs0KAwAJ