Added missing check

src/QuantPTQ.cpp

@@ -397,7 +397,10 @@ void normalizeParameters(std::shared_ptr<GraphView> graphView)
             if (nodeHasBias)
             {
                 std::shared_ptr<Tensor> biasTensor = getBiasTensor(node);
-                rescaleTensor(biasTensor, accumulatedRatios[node->name()] );
+                // Check that a bias is present (as it is optional)
+                if (biasTensor) {
+                    rescaleTensor(biasTensor, accumulatedRatios[node->name()] );
+                }
             }
 
         }