Contour Map: Replace assert and crash with error messages

[magnesj]

Replace crash with a valid empty return value and error message. The error message can be propagated when the receiving system is updated.

[0] performCrashLogging at ResInsight/ApplicationExeCode/RiaMainTools.cpp:147
[1] manageSegFailureSA(int, siginfo_t*, void*) at ResInsight/ApplicationExeCode/RiaMainTools.cpp:227
[3] RigEclipseContourMapProjection::calculateColumnResult(RigCaseCellResultsData&, RigContourMapCalculator::ResultAggregationType, int, RigFloodingSettings&) at ResInsight/ApplicationLibCode/ReservoirDataModel/ContourMap/RigEclipseContourMapProjection.cpp:202
[4] RigEclipseContourMapProjection::generateResults(RigEclipseContourMapProjection const&, RigContourMapGrid const&, RigCaseCellResultsData&, RigEclipseResultAddress const&, RigContourMapCalculator::ResultAggregationType, int, RigFloodingSettings&) at ResInsight/ApplicationLibCode/ReservoirDataModel/ContourMap/RigEclipseContourMapProjection.cpp:126
[5] RigEclipseContourMapProjection::generateResults(RigEclipseResultAddress const&, RigContourMapCalculator::ResultAggregationType, int, RigFloodingSettings&) const at ResInsight/ApplicationLibCode/ReservoirDataModel/ContourMap/RigEclipseContourMapProjection.cpp:83
[6] RimEclipseContourMapProjection::generateResults(int) const at ResInsight/ApplicationLibCode/ProjectDataModel/ContourMap/RimEclipseContourMapProjection.cpp:189
[7] RimEclipseContourMapProjection::computeMinMaxValuesAllTimeSteps() at ResInsight/ApplicationLibCode/ProjectDataModel/ContourMap/RimEclipseContourMapProjection.cpp:376
[8] RimContourMapProjection::minmaxValuesAllTimeSteps() at ResInsight/ApplicationLibCode/ProjectDataModel/ContourMap/RimContourMapProjection.cpp:478
[9] RimEclipseContourMapProjection::updateLegend() at ResInsight/ApplicationLibCode/ProjectDataModel/ContourMap/RimEclipseContourMapProjection.cpp:117
[10] RimEclipseContourMapView::onUpdateLegends() at ResInsight/ApplicationLibCode/ProjectDataModel/ContourMap/RimEclipseContourMapView.cpp:445
[11] RimEclipseContourMapView::updateGeometry() at ResInsight/ApplicationLibCode/ProjectDataModel/ContourMap/RimEclipseContourMapView.cpp:284
[12] Rim3dView::updateDisplayModelForCurrentTimeStepAndRedraw() at ResInsight/ApplicationLibCode/ProjectDataModel/Rim3dView.cpp:673
[13] RiuViewer::setCurrentFrame(int) at ResInsight/ApplicationLibCode/UserInterface/RiuViewer.cpp:1008
[14] RimEclipseView::onCreateDisplayModel() at ResInsight/ApplicationLibCode/ProjectDataModel/RimEclipseView.cpp:791
[15] RimEclipseContourMapView::onCreateDisplayModel() at ResInsight/ApplicationLibCode/ProjectDataModel/ContourMap/RimEclipseContourMapView.cpp:205
[16] Rim3dView::createDisplayModelAndRedraw() at ResInsight/ApplicationLibCode/ProjectDataModel/Rim3dView.cpp:718
[17] RiaViewRedrawScheduler::updateAndRedrawScheduledViews() at ResInsight/ApplicationLibCode/Application/RiaViewRedrawScheduler.cpp:93
[22] RiaGuiApplication::notify(QObject*, QEvent*) at ResInsight/ApplicationLibCode/Application/RiaGuiApplication.cpp:1823
[32] main at ResInsight/ApplicationExeCode/RiaMain.cpp:226
[33] __libc_start_main at :0