The init snapshot dumped functions with a line-based filter:
declare -f | grep -vE '^_[^_]'
That strips a function's *header* line (e.g. `_foo () `) but leaves the
orphaned `{ ... }` body behind, corrupting the snapshot that is sourced
before every command. Sourcing the torn snapshot runs leftover body code
and breaks subsequent commands (intermittent exit 127).
- Filter private (`_`-prefixed) functions by NAME via `declare -F` and
dump only the wanted whole definitions, so a body is never torn. Guard
against an empty name list (bare `declare -f` dumps everything).
- Treat a non-zero bootstrap exit code as snapshot-init failure, so
execution safely falls back to login-shell-per-command mode.
- Add a regression test asserting snapshot_ready stays false when
bootstrap exits non-zero.
Preserves the atomic-write ($BASHPID temp + mv -f) machinery from #38249.
2a3dbcaf46