If bad or unrecognised parameters are specified after JSON output is
requested, `usage()` will try to output null JSON object before the
writer is created.
To prevent this, create the writer as soon as the `--json` option is
parsed.
Fixes: 004b45c0e51a ("tools: bpftool: provide JSON output for all possible commands")
Reported-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
9b85c2d450