struct slowlog_entry *slowlog_create_sub_entry(struct command *cmd, int64_t total_latency)
{
    ...
    int64_t max_remote_latency = 0;
    struct command *c, *slowest_sub_cmd = NULL;
    STAILQ_FOREACH(c, &cmd->sub_cmds, sub_cmd_next) {
        // When this command fails because of not being able to connect to redis,
        // `remote_latency` will be zero (or maybe nagative) which result in a NULL `slowest_sub_cmd`.
        int64_t remote_latency = c->rep_time[1] - c->rep_time[0];
        if (remote_latency > max_remote_latency) {
            max_remote_latency = remote_latency;
            slowest_sub_cmd = c;
        }
    }
   // NULL `slowest_sub_cmd` will create a crash here.
    return slowlog_create_entry(slowest_sub_cmd, max_remote_latency / 1000, total_latency);
}