Core dump in resolve handler

[v1talM]

existing_addr = &dynamic_server->server->addrs[j]; maybe caused core dump while dynamic_server->server have no valid sockaddr:

(gdb) p *(ngx_http_upstream_dynamic_server_conf_t *) ctx->data
$1 = {cur_node = 0x0, pool_queue = {prev = 0x1e32e88, next = 0x1e32e88}, pool_queue_len = 0, resolve_num = 1, server = 0x190ea40, upstream_conf = 0x19076b8, origin_url = {len = 42, 
    data = 0x190ebe4 "proa.b.x:8345"}, host = {len = 37, data = 0x190ebe4 "proa.b.x:8345"}, port = 8435, timer = {
    data = 0x1e32e80, write = 0, accept = 0, instance = 0, active = 0, disabled = 0, ready = 0, oneshot = 0, complete = 0, eof = 0, error = 0, timedout = 1, timer_set = 0, delayed = 0, 
    deferred_accept = 0, pending_eof = 0, posted = 0, closed = 0, channel = 0, resolver = 0, cancelable = 0, available = 0, 
    handler = 0x71d200 <ngx_http_upstream_dynamic_server_timer_hook>, index = 0, log = 0x16a2af8, timer = {key = 0, left = 0x0, right = 0x0, parent = 0x0, color = 0 '\000', 
      data = 0 '\000'}, queue = {prev = 0x0, next = 0x0}}, refresh_interval = 15, original_init_peer = 0x699000 <ngx_http_upstream_init_round_robin_peer>}
(gdb) p *(ngx_http_upstream_server_t*) 0x190ea40
$2 = {name = {len = 38, data = 0x1ceb66f "a.b.x:9102"}, addrs = 0x1aebaf0, naddrs = 1, weight = 25, max_conns = 0, max_fails = 1, fail_timeout = 3, 
  slow_start = 0, down = 0, backup = 0}
(gdb) p *(ngx_addr_t *) 0x1aebaf0
$3 = {sockaddr = 0x0, socklen = 0, name = {len = 0, data = 0x0}}
(gdb)