ENH: Do not fatal on spoke failure, just warn.

Should never happen when there is a suitable number of spokes - this was only
seen for-real in a mesh with spokes = 1;

src/mesh/conformalVoronoiMesh/conformalVoronoiMesh/conformalVoronoiMesh.C

@@ -160,9 +160,19 @@ Foam::tensor Foam::conformalVoronoiMesh::requiredAlignment
 
     if (closestSpokeSurface == -1)
     {
-        FatalErrorIn("conformalVoronoiMesh::requiredAlignment")
-            << "No secondary surface hit found in spoke search."
-            << nl << exit(FatalError);
+        WarningIn
+        (
+            "conformalVoronoiMesh::requiredAlignment"
+            "("
+                "const Foam::point& pt"
+            ") const"
+        )
+            << "No secondary surface hit found in spoke search "
+            << "using " << s
+            << " spokes, try increasing alignmentSearchSpokes."
+            << endl;
+
+        return I;
     }
 
     // Auxiliary alignment generated by spoke intersection normal.