qgis/Quantum-GIS — pull request #495 by matthias-kuhn (2013-04-02 13:48:25+00:00)
Title: [FIX #7485]: Don't crash when expression fails to parse in dual view/preview column.

Don't crash when QgsExpression parser fails to parse a preview column (e.g. column without name)

Also removed throwing exception as this has been discouraged.