Error messages not fully captured

[uniomni]

If an error occurs, it is currently reported in the GUI and there is an option to see the stack trace.
However, the error message is not the full Python message.

For example if an impact function has a key error (e.g non existing key 'public_building' in a dictionary), the GUI reports:

No impact layer was calculated. Error message: Calculation error encountered: Problem:
'public_building'

It should have said:
KeyError: 'public_building'

The stack trace is great except that the label Toggle traceback appears twice (and so does the Problem tag)

This is not urgent, but would be good to sort out as it helps development.

[timlinux]

Also causes #162

[uniomni]

Similar problem today:
No impact layer was calculated. Error message: Terjadi kesalahan perhitungan: Problem:
2

Terjadi kesalahan perhitungan:
Problem:

2

Toggle traceback...

File "/home/nielso/.qgis/python/plugins/inasafe-dev/gui/is_impact_calculator_thread.py", line 146, in run

theFunction=self._function)

File "/home/nielso/.qgis/python/plugins/inasafe-dev/gui/is_safe_interface.py", line 417, in calculateSafeImpact

return safe_calculate_impact(theLayers, theFunction)

File "/home/nielso/.qgis/python/plugins/inasafe-dev/engine/core.py", line 56, in calculate_impact

F = impact_function.run(layers)

File "/home/nielso/.qgis/python/plugins/inasafe-dev/impact_functions/earthquake/padang_building_impact_model.py", line 102, in run

damage_params = damage_curves[building_type]

The problem here is to do with key error in the dictionary damage_curves

[uniomni]

See also issue #174

[timlinux]

Reopenied as we still have the 'toggle twice issue''

[uniomni]

Still not seeing the error message in relation to issue #174 - maybe there isn't one?
Could we show a token e.g. None in case the error message string is empty?

E.g. either

Calculation Error: Input layers did not overlap
or
Calculation Error: None

[timlinux]

Ok I believe this is all neat and tidy now with no double exceptions and the second tier exception being reported as a string. I am going to have one more little pass at beautifying the stringified exception that is pulled over from SAFE by putting the trace items into an html list.

[uniomni]

Looks good!