Documented richer-than-cstage divergence: cstage cmd/wcc/check.c
:1708 walks N_YIELD's lhs but does NOT stamp `n->type` — yield is
statement-shaped there. Wwstage's A.6.2 invariant requires every
post-dispatch kind have `type_` set, so this commit draws in the
leaner side. Yield's value type is the operand's type per Hare's
unified stmt/expr AST (ref/hare/hare/ast/expr.ha:449-461 —
`yield_expr` is on L459 inside the `expr` sum). Bare `yield;`
(no operand) stamps void.
Same nil-tolerant pass-through template as A.6.2.0e N_SPREAD,
plus the bare-yield void variant.
A.6.2 step 6 of 8 (γ order). N_MATCH-as-expression next, then
the assertion closer.
`make test-unit` green; full `make test` batched per option B.
Hojun-Cho
f0a8a37077