WriteJSON check response write error

[lpxxn]

we need to check w.Write(jsonBytes) error.

there have an case, i have encountered:
when i write wrong number of response Header Content-Length
the w.Write(jsonBytes) will throw an err "http: wrote more than the declared Content-Length"

w.written += int64(lenData) // ignoring errors, for errorKludge        

if w.contentLength != -1 && w.written > w.contentLength {       

	return 0, ErrContentLength       

}       

but gin did not throw the error, and response body is empty

[codecov]

Codecov Report

Merging #1653 into master will increase coverage by 1.06%.
The diff coverage is 33.33%.

@@            Coverage Diff             @@
##           master    #1653      +/-   ##
==========================================
+ Coverage   98.48%   99.55%   +1.06%     
==========================================
  Files          41       23      -18     
  Lines        2042      445    -1597     
==========================================
- Hits         2011      443    -1568     
+ Misses         19        1      -18     
+ Partials       12        1      -11

Impacted Files	Coverage Δ
render/json.go	96.96% <33.33%> (+10.48%)	⬆️
render/text.go	100% <0%> (ø)	⬆️
logger.go
debug.go
tree.go
utils.go
response_writer.go
fs.go
response_writer_1.8.go
path.go
... and 12 more

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[appleboy]

@lpxxn Please add the testing case to improve code coverage.

[lpxxn]

@lpxxn Please add the testing case to improve code coverage.

@appleboy i have write the testing function, check the panic of c.JSON when make wrong Content-Length

[thinkerou]

#1739 fixed! thanks @lpxxn