Fem: Fix crash in pipeline

src/Mod/Fem/App/FemPostPipeline.cpp

@@ -571,6 +571,9 @@ void FemPostPipeline::setTimeInfo(const std::string& frameType, const Base::Unit
         fd_block->AddArray(timeInfo);
         for (unsigned int i = 0; i < multiblock->GetNumberOfBlocks(); ++i) {
             vtkDataObject* grid = multiblock->GetBlock(i);
+            if (!grid) {
+                continue;
+            }
             auto fd_grid = grid->GetFieldData();
             if (fd_grid) {
                 // add time info to each grid

src/Mod/Fem/App/VTKExtensions/vtkFemFrameSourceAlgorithm.cpp

@@ -80,10 +80,9 @@ std::vector<double> vtkFemFrameSourceAlgorithm::getFrameValues()
     std::vector<double> tFrames(nblocks);
 
     for (unsigned long i = 0; i < nblocks; i++) {
-
         vtkDataObject* block = multiblock->GetBlock(i);
         // check if the TimeValue field is available
-        if (!block->GetFieldData()->HasArray("TimeValue")) {
+        if (!block || !block->GetFieldData() || !block->GetFieldData()->HasArray("TimeValue")) {
             // a frame with no valid value is a undefined state
             return std::vector<double>();
         }
@@ -94,7 +93,6 @@ std::vector<double> vtkFemFrameSourceAlgorithm::getFrameValues()
             // a frame with no valid value is a undefined state
             return std::vector<double>();
         }
-
         tFrames[i] = vtkFloatArray::SafeDownCast(TimeValue)->GetValue(0);
     }