Fix #404
Fix #404

Some new code was assuming the box required is always non-empty. Not so.


Former-commit-id: 20b16090b5a75b9f0ab799286a1a6ea4ddc1d8a3
Trass3r/Halide,Trass3r/Halide,darkbuck/Halide,Trass3r/Halide,darkbuck/Halide,darkbuck/Halide,darkbuck/Halide,Trass3r/Halide,Trass3r/Halide,Trass3r/Halide,Trass3r/Halide,darkbuck/Halide,darkbuck/Halide,darkbuck/Halide