Crash in Account view after undo

[hsoft]

@@@
Application Identifier: com.hardcoded_software.moneyguru
Application Version: 1.7.6

Traceback (most recent call last):
File "/Applications/moneyGuru.app/Contents/Resources/mg_cocoa.plugin/Contents/Resources/mg_cocoa.py", line 233, in undo
File "core/document.pyc", line 1122, in undo
File "hsutil/notify.pyc", line 17, in notify
File "hsutil/notify.pyc", line 35, in dispatch
File "core/gui/chart.pyc", line 24, in _data_changed
File "core/gui/graph.pyc", line 67, in compute
File "core/gui/bar_graph.pyc", line 63, in compute_data
File "core/gui/bar_graph.pyc", line 25, in _get_cash_flow
File "core/gui/bar_graph.pyc", line 20, in _currency
AttributeError: 'NoneType' object has no attribute 'currency'
@@@

I reproduced the error by adding a new income account, showing it, and then undoing the account creation.

[hsoft]

(from [6c5f5a853e47]) [#132 state:fixed] Fixed crash when undoing account creation while viewing it in the account view.
http://bitbucket.org/hsoft/moneyguru/changeset/6c5f5a853e47/