seccomp: possible error leak

[eriksjolund]

If get_seccomp_operator() creates an error here

crun/src/libcrun/seccomp.c

Lines 124 to 125 in e954750

	crun_make_error (err, 0, "seccomp get operator `%s`", name);
	return 0;

then the error would be leaked here

crun/src/libcrun/seccomp.c

Lines 798 to 800 in e954750

	arg_cmp[k].op = get_seccomp_operator (op, err);
	if (arg_cmp[k].op == 0)
	return crun_make_error (err, 0, "get_seccomp_operator");

I noticed this when reading the code.