fix debug info in errors.c

git-svn-id: https://yap.svn.sf.net/svnroot/yap/trunk@453 b08c6af1-5177-4d33-ba66-4b1c6b8b522a

C/errors.c

@@ -363,7 +363,7 @@ Error (yap_error_number type, Term where, char *format,...)
     PrologMode &= ~AbortMode;
     PrologMode |= InErrorMode;
   } else {
-    plwrite( where, DebugPutc, 0);
+    if (type != SYNTAX_ERROR)
       where = CopyTerm(Deref(where));
     if (IsVarTerm(where)) {
       /* we must be careful someone gave us a copy to a local variable */