diff --git a/src/App/ObjectIdentifier.cpp b/src/App/ObjectIdentifier.cpp
index c6aadd936e..aa1112b9c9 100644
--- a/src/App/ObjectIdentifier.cpp
+++ b/src/App/ObjectIdentifier.cpp
@@ -1463,31 +1463,36 @@ std::string ObjectIdentifier::String::toString(bool toPython) const
 void ObjectIdentifier::String::checkImport(const App::DocumentObject *owner,
         const App::DocumentObject *obj, String *objName)
 {
-    if(owner && owner->getDocument() &&
-       str.size() &&
-       ExpressionParser::ExpressionImporter::reader())
-    {
+    if(owner && owner->getDocument() && str.size() &&
+       ExpressionParser::ExpressionImporter::reader()) {
         auto reader = ExpressionParser::ExpressionImporter::reader();
-        if(obj || objName) {
+        if (obj || objName) {
             bool restoreLabel = false;
             str = PropertyLinkBase::importSubName(*reader,str.c_str(),restoreLabel);
-            if(restoreLabel) {
-                if(!obj) {
+            if (restoreLabel) {
+                if (!obj) {
                     std::bitset<32> flags;
                     obj = getDocumentObject(owner->getDocument(),*objName,flags);
-                    if(!obj)
+                    if (!obj) {
                         FC_ERR("Cannot find object " << objName->toString());
+                    }
+                }
+
+                if (obj) {
+                    PropertyLinkBase::restoreLabelReference(obj,str);
                 }
-                PropertyLinkBase::restoreLabelReference(obj,str);
             }
-        } else if (str.back()!='@')
+        }
+        else if (str.back()!='@') {
             str = reader->getName(str.c_str());
-        else{
+        }
+        else {
             str.resize(str.size()-1);
             auto mapped = reader->getName(str.c_str());
             auto obj = owner->getDocument()->getObject(mapped);
-            if(!obj)
+            if (!obj) {
                 FC_ERR("Cannot find object " << str);
+            }
             else {
                 isString = true;
                 forceIdentifier = false;
diff --git a/src/App/PropertyLinks.cpp b/src/App/PropertyLinks.cpp
index 8cfd137085..5b2005bb71 100644
--- a/src/App/PropertyLinks.cpp
+++ b/src/App/PropertyLinks.cpp
@@ -613,7 +613,7 @@ void PropertyLinkList::setSize(int newSize)
 {
     for(int i=newSize;i<(int)_lValueList.size();++i) {
         auto obj = _lValueList[i];
-        if(!obj && !obj->getNameInDocument())
+        if (!obj || !obj->getNameInDocument())
             continue;
         _nameMap.erase(obj->getNameInDocument());
 #ifndef USE_OLD_DAG
diff --git a/src/Mod/Fem/App/FemVTKTools.cpp b/src/Mod/Fem/App/FemVTKTools.cpp
index 32737ce39c..29e0c291a7 100644
--- a/src/Mod/Fem/App/FemVTKTools.cpp
+++ b/src/Mod/Fem/App/FemVTKTools.cpp
@@ -576,13 +576,14 @@ App::DocumentObject* FemVTKTools::readResult(const char* filename, App::Document
 
     vtkSmartPointer<vtkDataSet> dataset = ds;
     App::DocumentObject* result = NULL;
-    if(!res)
-        result = res;
-    else
+
+    if (res)
     {
         Base::Console().Message("FemResultObject pointer is NULL, trying to get the active object\n");
         if(obj->getTypeId() == Base::Type::fromName("Fem::FemResultObjectPython"))
+        {
             result = obj;
+        }
         else
         {
             Base::Console().Message("the active object is not the correct type, do nothing\n");
@@ -594,11 +595,17 @@ App::DocumentObject* FemVTKTools::readResult(const char* filename, App::Document
     std::unique_ptr<FemMesh> fmesh(new FemMesh());
     importVTKMesh(dataset, fmesh.get());
     static_cast<PropertyFemMesh*>(mesh->getPropertyByName("FemMesh"))->setValuePtr(fmesh.release());
-    static_cast<App::PropertyLink*>(result->getPropertyByName("Mesh"))->setValue(mesh);
-    // PropertyLink is the property type to store DocumentObject pointer
 
-    //vtkSmartPointer<vtkPointData> pd = dataset->GetPointData();
-    importFreeCADResult(dataset, result);
+    if (result)
+    {
+        // PropertyLink is the property type to store DocumentObject pointer
+        App::PropertyLink* link = dynamic_cast<App::PropertyLink*>(result->getPropertyByName("Mesh"));
+        if (link)
+            link->setValue(mesh);
+
+        //vtkSmartPointer<vtkPointData> pd = dataset->GetPointData();
+        importFreeCADResult(dataset, result);
+    }
 
     pcDoc->recompute();
     Base::Console().Log("    %f: Done \n", Base::TimeInfo::diffTimeF(Start, Base::TimeInfo()));
@@ -866,6 +873,7 @@ void FemVTKTools::exportFreeCADResult(const App::DocumentObject* result, vtkSmar
             field = static_cast<App::PropertyFloatList*>(res->getPropertyByName(it->first.c_str()));
         else
             Base::Console().Error("PropertyFloatList %s not found \n", it->first.c_str());
+
         if (field && field->getSize() > 0) {
             //if (nPoints != field->getSize())
             //    Base::Console().Error("Size of PropertyFloatList = %d, not equal to vtk mesh node count %d \n", field->getSize(), nPoints);
@@ -890,9 +898,10 @@ void FemVTKTools::exportFreeCADResult(const App::DocumentObject* result, vtkSmar
 
             grid->GetPointData()->AddArray(data);
             Base::Console().Log("    The PropertyFloatList %s was exported to VTK scalar list: %s\n", it->first.c_str(), it->second.c_str());
-       }
-        else
+        }
+        else if (field) {
             Base::Console().Log("    PropertyFloatList NOT exported to vtk: %s size is: %i\n", it->first.c_str(), field->getSize());
+        }
     }
 
     Base::Console().Log("End: Create VTK result data from FreeCAD result data.\n");
diff --git a/src/Mod/Import/App/ImportOCAF2.cpp b/src/Mod/Import/App/ImportOCAF2.cpp
index 2478ba9c09..f5428ad38b 100644
--- a/src/Mod/Import/App/ImportOCAF2.cpp
+++ b/src/Mod/Import/App/ImportOCAF2.cpp
@@ -1129,7 +1129,8 @@ TDF_Label ExportOCAF2::exportObject(App::DocumentObject* parentObj,
     App::DocumentObject *obj;
     auto shape = Part::Feature::getTopoShape(parentObj,sub,false,0,&obj,false,!sub);
     if(!obj || shape.isNull()) {
-        FC_WARN(obj->getFullName() << " has null shape");
+        if (obj)
+            FC_WARN(obj->getFullName() << " has null shape");
         return TDF_Label();
     }
 
diff --git a/src/Mod/Part/App/AppPartPy.cpp b/src/Mod/Part/App/AppPartPy.cpp
index aa407ac12a..835c794fe8 100644
--- a/src/Mod/Part/App/AppPartPy.cpp
+++ b/src/Mod/Part/App/AppPartPy.cpp
@@ -2210,16 +2210,18 @@ private:
         if (!PyArg_ParseTuple(args.ptr(), "sss",&sub,&mapped,&element))
             throw Py::Exception();
         std::string subname(sub);
-        if(subname.size() && subname[subname.size()-1]!='.')
+        if (subname.size() && subname[subname.size()-1]!='.')
             subname += '.';
-        if(mapped && mapped[0]) {
-            if(!Data::ComplexGeoData::isMappedElement(mapped))
+        if (mapped && mapped[0]) {
+            if (!Data::ComplexGeoData::isMappedElement(mapped))
                 subname += Data::ComplexGeoData::elementMapPrefix();
             subname += mapped;
-            if(element && element[0] && subname[subname.size()-1]!='.')
-                subname += '.';
         }
-        subname += element;
+        if (element && element[0]) {
+            if (subname.size() && subname[subname.size()-1]!='.')
+                subname += '.';
+            subname += element;
+        }
         return Py::String(subname);
     }
 };
diff --git a/src/Mod/Part/Gui/ViewProviderExt.cpp b/src/Mod/Part/Gui/ViewProviderExt.cpp
index 709873bc3d..70e3548aeb 100644
--- a/src/Mod/Part/Gui/ViewProviderExt.cpp
+++ b/src/Mod/Part/Gui/ViewProviderExt.cpp
@@ -929,11 +929,10 @@ void ViewProviderPartExt::reload()
 
 void ViewProviderPartExt::updateData(const App::Property* prop)
 {
-    const char *propName = prop?prop->getName():"";
-    if(propName  && (strcmp(propName,"Shape")==0 || strstr(propName,"Touched")!=0))
-    {
+    const char *propName = prop->getName();
+    if (propName && (strcmp(propName, "Shape") == 0 || strstr(propName, "Touched") != nullptr)) {
         // calculate the visual only if visible
-        if (isUpdateForced()||Visibility.getValue())
+        if (isUpdateForced() || Visibility.getValue())
             updateVisual();
         else 
             VisualTouched = true;
diff --git a/src/Mod/Spreadsheet/Gui/SpreadsheetView.cpp b/src/Mod/Spreadsheet/Gui/SpreadsheetView.cpp
index c12056799c..1255661ef8 100644
--- a/src/Mod/Spreadsheet/Gui/SpreadsheetView.cpp
+++ b/src/Mod/Spreadsheet/Gui/SpreadsheetView.cpp
@@ -407,7 +407,7 @@ void SheetView::currentChanged ( const QModelIndex & current, const QModelIndex
 void SheetView::updateCell(const App::Property *prop)
 {
     try {
-        if (sheet && prop == &sheet->Label) {
+        if (prop == &sheet->Label) {
             QString cap = QString::fromUtf8(sheet->Label.getValue());
             setWindowTitle(cap);
         }
diff --git a/src/Mod/TechDraw/Gui/QGIViewBalloon.cpp b/src/Mod/TechDraw/Gui/QGIViewBalloon.cpp
index 64802b0994..e9754da795 100644
--- a/src/Mod/TechDraw/Gui/QGIViewBalloon.cpp
+++ b/src/Mod/TechDraw/Gui/QGIViewBalloon.cpp
@@ -366,7 +366,7 @@ void QGIViewBalloon::setViewPartFeature(TechDraw::DrawViewBalloon *balloon)
     DrawView* balloonParent = nullptr;
     double scale = 1.0;
     App::DocumentObject* docObj = balloon->SourceView.getValue();
-    if (docObj == nullptr) {
+    if (docObj) {
         balloonParent = dynamic_cast<DrawView*>(docObj);
         if (balloonParent)
             scale = balloonParent->getScale();
diff --git a/src/Mod/TechDraw/Gui/TaskCenterLine.cpp b/src/Mod/TechDraw/Gui/TaskCenterLine.cpp
index 9f97bd3ae7..182bdf80d3 100644
--- a/src/Mod/TechDraw/Gui/TaskCenterLine.cpp
+++ b/src/Mod/TechDraw/Gui/TaskCenterLine.cpp
@@ -97,8 +97,10 @@ TaskCenterLine::TaskCenterLine(TechDraw::DrawViewPart* partFeat,
     if (m_cl == nullptr) {         //checked by CommandAnnotate.  Should never happen.
         Base::Console().Message("TCL::TCL() - no centerline found\n");
     }
-    m_type = m_cl->m_type;
-    m_mode = m_cl->m_mode;
+    else {
+        m_type = m_cl->m_type;
+        m_mode = m_cl->m_mode;
+    }
 
     setUiEdit();
 }
diff --git a/src/Mod/TechDraw/Gui/TaskDetail.cpp b/src/Mod/TechDraw/Gui/TaskDetail.cpp
index b7a68669c7..a9bcdc2df7 100644
--- a/src/Mod/TechDraw/Gui/TaskDetail.cpp
+++ b/src/Mod/TechDraw/Gui/TaskDetail.cpp
@@ -95,6 +95,7 @@ TaskDetail::TaskDetail(TechDraw::DrawViewPart* baseFeat):
     m_basePage = m_baseFeat->findParentPage();
     if (m_basePage == nullptr) {
         Base::Console().Error("TaskDetail - bad parameters - base page.  Can not proceed.\n");
+        return;
     }
 
     m_baseName = m_baseFeat->getNameInDocument();
diff --git a/src/Mod/TechDraw/Gui/TaskLeaderLine.cpp b/src/Mod/TechDraw/Gui/TaskLeaderLine.cpp
index 6f63cb7873..a4b8739a80 100644
--- a/src/Mod/TechDraw/Gui/TaskLeaderLine.cpp
+++ b/src/Mod/TechDraw/Gui/TaskLeaderLine.cpp
@@ -421,7 +421,9 @@ void TaskLeaderLine::createLeaderFeature(std::vector<Base::Vector3d> converted)
     if (m_basePage != nullptr) {
         m_basePage->touch();
     }
-    m_lineFeat->requestPaint();
+    if (m_lineFeat != nullptr) {
+        m_lineFeat->requestPaint();
+    }
 }
 
 void TaskLeaderLine::updateLeaderFeature(void)