-CopyError::CopyError (string m, int n)
- : runtime_error (String::compose("%1 (%2)", m, n))
+
+GLError::GLError (char const* message)
+ : runtime_error (message)
+{
+
+}
+
+
+CopyError::CopyError (string m, optional<int> n)
+ : runtime_error (String::compose("%1%2", m, n ? String::compose(" (%1)", *n) : ""))