Fix crashes reported by crash telemetry

* Use guarded pointer for delayed plot updates

The cached result definition can be deleted before the delayed update is
executed, causing a crash in the PVT and relative permeability plot panels.

* Guard against fracture definition without conductivity result

The list of conductivity result names is empty for some fracture
definitions, causing an out of range access when computing statistics.

* Guard against missing data source in custom VFP plot

The data source of a VFP table can be null, and the VFP tables are not
available until the data has been imported.

ApplicationLibCode/UnitTests/RiuPlotUpdater-Test.cpp

@@ -0,0 +1,59 @@
+#include "gtest/gtest.h"
+
+#include "RimEclipseResultDefinition.h"
+
+#include "Riu3dSelectionManager.h"
+#include "RiuPlotUpdater.h"
+
+#include <QWidget>
+
+//--------------------------------------------------------------------------------------------------
+///
+//--------------------------------------------------------------------------------------------------
+class TestPlotUpdater : public RiuPlotUpdater
+{
+public:
+    void storeSelection( const RiuEclipseSelectionItem* selectionItem ) { storeDelayedInformation( selectionItem ); }
+
+    int queryCount() const { return m_queryCount; }
+
+protected:
+    void     clearPlot() override {}
+    QWidget* plotPanel() override { return nullptr; }
+
+    bool queryDataAndUpdatePlot( const RimEclipseResultDefinition* eclipseResDef, size_t, size_t, size_t ) override
+    {
+        m_queryCount++;
+        return true;
+    }
+
+private:
+    int m_queryCount = 0;
+};
+
+//--------------------------------------------------------------------------------------------------
+/// The result definition can be deleted between the selection change and the delayed update
+//--------------------------------------------------------------------------------------------------
+TEST( RiuPlotUpdaterTest, DelayedUpdateAfterResultDefinitionIsDeleted )
+{
+    auto* resultDefinition = new RimEclipseResultDefinition;
+
+    RiuEclipseSelectionItem selectionItem( nullptr,
+                                           resultDefinition,
+                                           0,
+                                           0,
+                                           0,
+                                           0,
+                                           cvf::Color3f( 1.0f, 0.0f, 0.0f ),
+                                           cvf::StructGridInterface::NO_FACE,
+                                           cvf::Vec3d::ZERO );
+
+    TestPlotUpdater plotUpdater;
+    plotUpdater.storeSelection( &selectionItem );
+
+    delete resultDefinition;
+
+    plotUpdater.doDelayedUpdate();
+
+    EXPECT_EQ( 0, plotUpdater.queryCount() );
+}