more reasonable error message

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@37217 15284696-431f-4ddb-bdfa-cd5b030d7da7

imagery/i.atcorr/GeomCond.cpp

@@ -373,7 +373,7 @@ void GeomCond::parse()
 	landsat(tu);
 	break;
     }
-    default: G_warning(_("Unsupported format"));
+    default: G_fatal_error(_("Unsupported/unreadable format in control file (found igeom=%d)"), igeom);
     }