- _emitBranch now sets _genVisited on blocks before calling generateOwnCode
so that proc calls inside loop bodies can seed their error-handling
visited set from the main traversal, preventing loop-decision re-walk
- Add _noWalkNext flag on proc calls when error handling is active, so
_emitBranch skips redundant nextFlow walking (the success path was
already covered by the error-handling branch emission)
- Known issue: shared blocks that are direct roots of emitBranch (from
the shared set) may still be re-walked when they were already emitted
by a downstream proc call's error-handling success path