`panic: runtime error: invalid memory address or nil pointer dereference` when scan CentOS5.5 about vuls HOT 2 CLOSED

> launchctl limit maxfiles
        maxfiles    256            unlimited

[May 17 10:29:43]  INFO [xxxxxx:22] (331/331) Scanned zlib-devel-1.2.3-3 -> 1.2.3-7.el5 : []
[May 17 10:29:43]  INFO [xxxxxx:22] Fetching CVE details...
WARN[0933] Failed to HTTP GET. retrying in 552.330144ms seconds. err: HTTP GET error: [Get http://127.0.0.1:1323/cves/CVE-2010-2431: EOF], url: http://127.0.0.1:1323/cves/CVE-2010-2431, resp: <nil>
WARN[0933] Failed to HTTP GET. retrying in 720.254544ms seconds. err: HTTP GET error: [Get http://127.0.0.1:1323/cves/CVE-2011-2748: EOF], url: http://127.0.0.1:1323/cves/CVE-2011-2748, resp: <nil>
WARN[0933] Failed to HTTP GET. retrying in 582.280027ms seconds. err: HTTP GET error: [Get http://127.0.0.1:1323/cves/CVE-2010-3704: dial tcp 127.0.0.1:1323: socket: too many open files], url: http://127.
0.0.1:1323/cves/CVE-2010-3704, resp: <nil>
WARN[0933] Failed to HTTP GET. retrying in 468.857094ms seconds. err: HTTP GET error: [Get http://127.0.0.1:1323/cves/CVE-2012-0061: dial tcp 127.0.0.1:1323: socket: too many open files], url: http://127.
0.0.1:1323/cves/CVE-2012-0061, resp: <nil>
WARN[0933] Failed to HTTP GET. retrying in 462.318748ms seconds. err: HTTP GET error: [Get http://127.0.0.1:1323/cves/CVE-2011-0281: dial tcp 127.0.0.1:1323: socket: too many open files], url: http://127.
0.0.1:1323/cves/CVE-2011-0281, resp: <nil>

-loop....-

{"time":"2016-05-17T10:29:44+09:00","remote_ip":"127.0.0.1","method":"GET","uri":"/cves/CVE-2011-2692","status":200, "latency":3995,"latency_human":"3.995597ms","rx_bytes":0,"tx_bytes":6178}
2016/05/17 10:29:44 http: Accept error: accept tcp 127.0.0.1:1323: accept: too many open files; retrying in 10ms
2016/05/17 10:29:44 http: Accept error: accept tcp 127.0.0.1:1323: accept: too many open files; retrying in 20ms
2016/05/17 10:29:44 http: Accept error: accept tcp 127.0.0.1:1323: accept: too many open files; retrying in 40ms
2016/05/17 10:29:44 http: Accept error: accept tcp 127.0.0.1:1323: accept: too many open files; retrying in 80ms

-loop...-