Error in byte-range mgmt

[kelson42]

I see this time to time in the log:

======================
Requesting : 
full_url  : /meta
method    : GET (0)
version   : HTTP/1.1
request#  : 247
headers   :
 - Accept : 'image/webp,image/apng,image/*,*/*;q=0.8'
 - Accept-Encoding : 'gzip, deflate'
 - Connection : 'close'
 - Host : 'library.kiwix.org'
 - User-Agent : 'Mozilla/5.0 (Windows NT 6.2; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) QtWebEngine/5.12.6 Chrome/69.0.3497.128 Safari/537.36'
 - X-Forwarded-For : '111.187.34.191'
 - X-Forwarded-Port : '80'
 - X-Forwarded-Proto : 'http'
 - X-Forwarded-Ssl : 'off'
 - X-Real-IP : '111.187.34.191'
arguments :
 - content : 'wikipedia_zh_medicine_maxi_2020-05'
 - name : 'favicon'
Parsed : 
full_url: /meta
url   : /meta
acceptEncodingDeflate : 1
has_range : 0
is_valid_url : 1
.............
Response :
httpResponseCode : 200
headers :
 - ETag: '"1591098928403549187/c"'
kiwix-serve: ../../SOURCE/kiwix-lib_release/src/server/byte_range.cpp:68: kiwix::ByteRange::ByteRange(kiwix::ByteRange::Kind, int64_t, int64_t): Assertion `last >= first' failed.
--
acceptEncodingDeflate : 1
has_range : 0
is_valid_url : 1
.............
** running handle_content
Response :
httpResponseCode : 404
headers :
 - Cache-Control: 'no-cache, no-store, must-revalidate'
 - Access-Control-Allow-Origin: '*'
 - Content-Type: 'text/html'
 - Content-Encoding: 'deflate'
 - Vary: 'Accept-Encoding'
Request time : 0.000577s

[veloman-yunkan]

IMO, the request causing the assertion failure precedes the request supplied in the log.

Looking at the source code, the problem is likely caused by a 0-sized entry (e.g. an empty CSS file).