raise user error/warning in wizard
Scenario:
1- There are two steps in a wizard.
2- Second step, validate some data, and raise user error when not invalid (with error details message).
3- Client crash with this error:
Traceback (most recent call last):
File "/home/resteve/virtualenv/try36/tryton/tryton/common/common.py", line 1319, in process
self.callback(return_)
File "/home/resteve/virtualenv/try36/tryton/tryton/gui/window/wizard.py", line 98, in callback
if 'view' in result:
TypeError: argument of type 'NoneType' is not iterable
Also, session wizard lost it.
Detect in v3.6. Working successfully in v3.4.