#13926 GeoMech well log: Guard against OOB indices when interpolating results

Bounds-check every gridResultValues access in interpolateGridResultValue
to prevent segfaults observed in interpolateInterfaceValues' OMP loop
when a result vector was empty or sized for a different result position
type. OOB now returns the infinity sentinel that matches the existing
undefined-value path and the initializeResultValues pre-fill, so
downstream invalid-value checks correctly skip these slots.

interpolateInterfaceValues additionally short-circuits and logs a
warning with the field/component name when the input result vector is
empty, instead of failing silently.

ApplicationLibCode/ReservoirDataModel/Well/RigGeoMechWellLogExtractor.cpp

@@ -1040,6 +1040,7 @@ T RigGeoMechWellLogExtractor::interpolateGridResultValue( RigFemResultPosEnum
 
     if ( resultPosType == RIG_ELEMENT )
     {
+        if ( elmIdx >= gridResultValues.size() ) return std::numeric_limits<T>::infinity();
         return gridResultValues[elmIdx];
     }
 
@@ -1055,11 +1056,13 @@ T RigGeoMechWellLogExtractor::interpolateGridResultValue( RigFemResultPosEnum
         // TODO: Should interpolate within the whole hexahedron. This requires converting to locals coordinates.
         // For now just pick the average value for the cell.
         size_t gridResultValueIdx = femPart->resultValueIdxFromResultPosType( resultPosType, static_cast<int>( elmIdx ), 0 );
-        T      sumOfVertexValues  = gridResultValues[gridResultValueIdx];
+        if ( gridResultValueIdx >= gridResultValues.size() ) return std::numeric_limits<T>::infinity();
+        T sumOfVertexValues = gridResultValues[gridResultValueIdx];
         for ( int i = 1; i < 8; ++i )
         {
             gridResultValueIdx = femPart->resultValueIdxFromResultPosType( resultPosType, static_cast<int>( elmIdx ), i );
-            sumOfVertexValues  = sumOfVertexValues + gridResultValues[gridResultValueIdx];
+            if ( gridResultValueIdx >= gridResultValues.size() ) return std::numeric_limits<T>::infinity();
+            sumOfVertexValues = sumOfVertexValues + gridResultValues[gridResultValueIdx];
         }
         return sumOfVertexValues * ( 1.0 / 8.0 );
     }
@@ -1092,6 +1095,7 @@ T RigGeoMechWellLogExtractor::interpolateGridResultValue( RigFemResultPosEnum
     nodeResultValues.reserve( 4 );
     for ( size_t i = 0; i < nodeResIdx.size(); ++i )
     {
+        if ( nodeResIdx[i] >= gridResultValues.size() ) return std::numeric_limits<T>::infinity();
         nodeResultValues.push_back( gridResultValues[nodeResIdx[i]] );
     }
     T interpolatedValue = cvf::GeometryTools::interpolateQuad<T>( v0,
@@ -1399,6 +1403,17 @@ std::vector<T> RigGeoMechWellLogExtractor::interpolateInterfaceValues( RigFemRes
     std::vector<T> interpolatedInterfaceValues;
     initializeResultValues( interpolatedInterfaceValues, intersections().size() );
 
+    if ( unscaledResultValues.empty() )
+    {
+        RiaLogging::warning( QString( "No result values available for %1 / %2 (time step %3, frame %4). "
+                                      "Well log curve will be empty." )
+                                 .arg( QString::fromStdString( nativeAddr.fieldName ) )
+                                 .arg( QString::fromStdString( nativeAddr.componentName ) )
+                                 .arg( timeStepIndex )
+                                 .arg( frameIndex ) );
+        return interpolatedInterfaceValues;
+    }
+
     const RigFemPart* femPart = m_caseData->femParts()->part( m_partId );
 
 #pragma omp parallel for