slate-hyperscript: can't build intentionally-invalid values, and bare <document produces extra text nodes

slate-hyperscript: can't build intentionally-invalid values, and bare <document produces extra text nodes: a task in MiMo-V2.6-RL-harbor-code: MiMo-V2.6-RL Code (Harbor) (Harbor dataset). I'm using slate-hyperscript to write test fixtures and ran into two things that look wrong.