Do not write empty patches into STL

src/triSurface/triSurface/geometricSurfacePatch/geometricSurfacePatch.H

@@ -65,6 +65,7 @@ class geometricSurfacePatch
         //- Index of patch in boundary
         label index_;
 
+
 public:
 
     //- Runtime type information

src/triSurface/triSurface/interfaces/STL/writeSTL.C

@@ -49,6 +49,11 @@ void triSurface::writeSTLASCII(Ostream& os) const
         // Print all faces belonging to this region
         const surfacePatch& patch = myPatches[patchI];
 
+        if (patch.size() == 0)
+        {
+            continue;
+        }
+
         os << "solid " << patch.name() << endl;
 
         for