Added further nullptr checks

src/field/distributors/KernelDistributor.h

@@ -78,6 +78,7 @@ public:
 
       WALBERLA_CHECK( !blockStorage_.expired() );
       auto blockStorage = blockStorage_.lock();
+      WALBERLA_CHECK_NOT_NULLPTR(blockStorage);
 
       Cell centerCell = blockStorage->getBlockLocalCell( block_, x, y, z );
 

src/field/distributors/NearestNeighborDistributor.h

@@ -75,6 +75,7 @@ public:
 
       WALBERLA_CHECK( !blockStorage_.expired() );
       auto blockStorage = blockStorage_.lock();
+      WALBERLA_CHECK_NOT_NULLPTR(blockStorage);
 
       Cell nearestCell = blockStorage->getBlockLocalCell( block_, x, y, z );
 

src/field/interpolators/KernelFieldInterpolator.h

@@ -122,6 +122,7 @@ public:
 
       WALBERLA_CHECK( !blockStorage_.expired() );
       auto blockStorage = blockStorage_.lock();
+      WALBERLA_CHECK_NOT_NULLPTR(blockStorage);
 
       Cell centerCell = blockStorage->getBlockLocalCell( block_, x, y, z );
 

src/field/interpolators/NearestNeighborFieldInterpolator.h

@@ -74,6 +74,7 @@ public:
 
       WALBERLA_CHECK( !blockStorage_.expired() );
       auto blockStorage = blockStorage_.lock();
+      WALBERLA_CHECK_NOT_NULLPTR(blockStorage);
 
       Cell nearestCell = blockStorage->getBlockLocalCell( block_, x, y, z );
 

src/field/interpolators/TrilinearFieldInterpolator.h

@@ -78,6 +78,7 @@ public:
 
       WALBERLA_CHECK( !blockStorage_.expired() );
       auto blockStorage = blockStorage_.lock();
+      WALBERLA_CHECK_NOT_NULLPTR(blockStorage);
 
       const real_t dx = blockStorage->dx( blockStorage->getLevel( block_ ) );
       const real_t dy = blockStorage->dy( blockStorage->getLevel( block_ ) );