Revert "temporarily make filler error into warning"
Revert "temporarily make filler error into warning"

This reverts commit e88d9ae45ceabeccd71e3b8011e9d76e2a8c441f.

The-OpenROAD-Project/OpenROAD,The-OpenROAD-Project/OpenROAD,QuantamHD/OpenROAD,QuantamHD/OpenROAD,The-OpenROAD-Project/OpenROAD,QuantamHD/OpenROAD,QuantamHD/OpenROAD,The-OpenROAD-Project/OpenROAD,QuantamHD/OpenROAD,The-OpenROAD-Project/OpenROAD