Regression Test: Do not access RimWellLogPlotCollection directly from desctructors

Regression tests are calling RimProject::reset(), and this function deletes the RimProject object.

ApplicationLibCode/ProjectDataModel/RimMainPlotCollection.cpp

@@ -160,6 +160,8 @@ RimMainPlotCollection::~RimMainPlotCollection()
 //--------------------------------------------------------------------------------------------------
 RimMainPlotCollection* RimMainPlotCollection::current()
 {
+    CVF_ASSERT( RimProject::current() );
+
     return RimProject::current()->mainPlotCollection();
 }