}
else
{
- y = me->get_bound (dir)->extent (common_y, Y_AXIS).center ();
+ Interval ii = me->get_bound (dir)->extent (common_y, Y_AXIS);
+ if (!ii.is_empty())
+ y = ii.center ();
details = scm_acons (ly_symbol2scm ("common-Y"), common_y->self_scm (), details);
}