#14906: FlowRateCurve: Guard against null plot curve in onLoadDataAndUpdate

Crash signature 9f3186ce4814.

RimWellFlowRateCurve::onLoadDataAndUpdate calls m_plotCurve->setTitle() after updateCurvePresentation(). Turning Show Curve off makes that call detach( true ), which deletes m_plotCurve and sets it to null, so the next line dereferences null.

Only call setTitle() when m_plotCurve is not null.

Call stack:
[3] RimWellFlowRateCurve::onLoadDataAndUpdate(bool) at ResInsight/ApplicationLibCode/ProjectDataModel/Flow/RimWellFlowRateCurve.cpp:166
[4] RimPlotCurve::loadDataAndUpdate(bool) at ResInsight/ApplicationLibCode/ProjectDataModel/RimPlotCurve.cpp:587
[5] non-virtual thunk to RimWellFlowRateCurve::fieldChangedByUi(caf::PdmFieldHandle const*, QVariant const&, QVariant const&) at ResInsight/ApplicationLibCode/ProjectDataModel/Flow/RimWellFlowRateCurve.h:63
[6] caf::PdmUiFieldHandle::notifyFieldChanged(QVariant const&, QVariant const&) at ResInsight/Fwk/AppFwk/cafProjectDataModel/cafPdmUiCore/cafPdmUiFieldHandle.cpp:75
[7] caf::PdmFieldUiCap<caf::PdmField<bool> >::setValueFromUiEditor(QVariant const&, bool) at ResInsight/Fwk/AppFwk/cafProjectDataModel/cafPdmUiCore/cafInternalPdmUiFieldCapability.inl:116
[8] caf::CmdFieldChangeExec::redo() at ResInsight/Fwk/AppFwk/cafCommand/cafCmdFieldChangeExec.cpp:139
[10] caf::CmdUiCommandSystemImpl::fieldChangedCommand(std::vector<caf::PdmFieldHandle*, std::allocator<caf::PdmFieldHandle*> > const&, QVariant const&) at ResInsight/Fwk/AppFwk/cafCommand/cafCmdUiCommandSystemImpl.cpp:146
[11] caf::PdmUiCommandSystemProxy::setUiValueToField(caf::PdmUiFieldHandle*, QVariant const&) at ResInsight/Fwk/AppFwk/cafProjectDataModel/cafPdmUiCore/cafPdmUiCommandSystemProxy.cpp:113
[12] caf::PdmUiTreeViewQModel::setData(QModelIndex const&, QVariant const&, int) at ResInsight/Fwk/AppFwk/cafUserInterface/cafPdmUiTreeViewQModel.cpp:761
[23] RiaGuiApplication::notify(QObject*, QEvent*) at ResInsight/ApplicationLibCode/Application/RiaGuiApplication.cpp:1828
[29] RiaGuiApplication::notify(QObject*, QEvent*) at ResInsight/ApplicationLibCode/Application/RiaGuiApplication.cpp:1828
[40] main at ResInsight/ApplicationExeCode/RiaMain.cpp:267
[41] __libc_start_main at :0

ApplicationLibCode/ProjectDataModel/Flow/RimWellFlowRateCurve.cpp

@@ -163,7 +163,7 @@ void RimWellFlowRateCurve::onLoadDataAndUpdate( bool updateParentPlot )
 {
     RimPlotCurve::updateCurvePresentation( updateParentPlot );
 
-    m_plotCurve->setTitle( createCurveAutoName() );
+    if ( m_plotCurve ) m_plotCurve->setTitle( createCurveAutoName() );
 
     if ( updateParentPlot )
     {