BUG: add a warning in star4ToFoam for .cel files containing only shell entries (#1425)

src/conversion/starcd/STARCDMeshReader.C

@@ -341,6 +341,12 @@ void Foam::fileFormats::STARCDMeshReader::readCells(const fileName& inputName)
     // construct cellFaces_ and possibly cellShapes_
     if (nCells <= 0)
     {
+        if (nShells != 0)
+        {
+            WarningInFunction
+                << inputName << "consists of only shell entries (typeId=4)."
+                << endl;
+        }
         FatalErrorInFunction
             << "no cells in file " << inputName
             << abort(FatalError);

src/conversion/starcd/STARCDMeshReader.H

@@ -36,6 +36,9 @@ Description
     - trimmed and degenerate cells are saved as polyhedral.
     - the boundaries corresponds to cells and their faces.
 
+Notes
+    - Shell entries are read, yet ignored.
+
 SourceFiles
     STARCDMeshReader.C