A text-leaf that mounts EMPTY passes insert()'s "must be inside <Text>" guard as
a Vue fragment anchor. If it later becomes non-empty via setText() — e.g.
`<Box><Text>label</Text>{{ maybe }}</Box>` where `maybe` goes ''->'hi' — it was
never re-validated, so non-empty bare text ended up directly under a <Box> and
paint silently DROPPED it (paintNode renders a text-leaf only via a <Text>/
<Transform> parent). Identical content mounted non-empty throws at insert, so the
same content either errored or silently vanished depending on render history.
Fix: setText() now re-runs the SAME rejectsTextLeaf() check insert() and
setElementText() use (the shared helper added in #179), throwing the same error
on an empty->non-empty transition into an invalid context. Throwing in the
patch/render phase is consistent with the "validate at render, not paint"
invariant and routes through the error boundary (rejects) rather than wedging. A
leaf inside <Text>, cleared back to "", or detached is a no-op; the common path
(text inside <Text>) is not rejected.
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Yunfei He
daf5e76dfd