当 response 的 Content-Encoding 是 gzip，同时 body 为空时程序崩溃 #305
Description
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Which platform are you running AnyProxy
Mac
The version of the AnyProxy
4.0.2
Your expected behavior of AnyProxy
无论什么请求，程序都正常运行
The actual behavior of AnyProxy
程序崩溃。
The log of the error
test request：
curl -x 127.0.0.1:8001 'https://beacon.tingyun.com/xhr1?pvid=e90422ff-80d8-470e-8de0-407d3f6bdbec&ref=https%3A%2F%2Ftest.example.com%2F&referrer=&key=vK4oZhra2XA&v=1.7.3&av=1.7.3&did=b51f4119-bd75-4fac-8050-e512ac7eddab&sid=f095450d-a0a9-4075-9256-55120e8be309&__r=1514212434717' -H 'Pragma: no-cache' -H 'Origin: https://test.example.com' -H 'Accept-Encoding: gzip, deflate, br' -H 'Accept-Language: zh-CN,zh;q=0.9,en-US;q=0.8,en;q=0.7' -H 'User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/63.0.3239.84 Safari/537.36' -H 'Content-Type: text/plain;charset=UTF-8' -H 'Accept: */*' -H 'Cache-Control: max-age=0' -H 'Referer: https://www.growingio.com/' -H 'Cookie: qtrans_cookie_test=qTranslate+Cookie+Test; Hm_lvt_93daecc2db29efa5d83566cf580e84af=1514212350; NTKF_T2D_CLIENTID=guest5DACA43B-1338-4E4B-FC1C-8E16DC2EE088; nTalk_CACHE_DATA={uid:kf_9212_ISME9754_guest5DACA43B-1338-4E,tid:1514212351021605}; Hm_lpvt_93daecc2db29efa5d83566cf580e84af=1514212352' -H 'Connection: keep-alive' --data-binary '{"xhr":[{"id":0,"req":"POST https://test.example.com","start":1514212433017,"du":32,"cb":0,"status":200,"err":0,"rec":0,"send":386},{"id":1,"req":"POST https://test.example.com/","start":1514212434573,"du":33,"cb":0,"status":200,"err":0,"rec":0,"send":12044}]}' --compressed
Log：
[AnyProxy Log][2017-12-25 22:43:59]: received https CONNECT request beacon.tingyun.com
[AnyProxy Log][2017-12-25 22:43:59]: will forward to local https server
[AnyProxy Log][2017-12-25 22:43:59]: [internal https]proxy server for beacon.tingyun.com established
[AnyProxy Log][2017-12-25 22:43:59]: received request to: POST beacon.tingyun.com/xhr1?pvid=e90422ff-80d8-470e-8de0-407d3f6bdbec&ref=https%3A%2F%2Ftest.example.com%2F&referrer=&key=vK4oZhra2XA&v=1.7.3&av=1.7.3&did=b51f4119-bd75-4fac-8050-e512ac7eddab&sid=f095450d-a0a9-4075-9256-55120e8be309&__r=1514212434717
[AnyProxy ERROR][2017-12-25 22:43:59]: got an uncaught exception, is there anything goes wrong in your rule file ?
TypeError: Cannot read property 'length' of null
at Gunzip.zlibBufferOnEnd (zlib.js:100:17)
at Gunzip.emit (events.js:164:20)
at endReadableNT (_stream_readable.js:1054:12)
at _combinedTickCallback (internal/process/next_tick.js:138:11)
at process._tickCallback (internal/process/next_tick.js:180:9)
[AnyProxy Log][2017-12-25 22:43:59]: destorying https connection : 127.0.0.1:63791
[AnyProxy Log][2017-12-25 22:43:59]: endding https cltSocket : 127.0.0.1:63791
[AnyProxy Log][2017-12-25 22:43:59]: clearing cache file...
[AnyProxy Log][2017-12-25 22:43:59]: closing webserver...