nil pointer exception in req() method

[MrVine]

Software

OS: Windows 10 x64
GO: go1.9.2 windows/amd64
gowebdav: latest version from master

go env

set GOARCH=386
set GOBIN=
set GOEXE=.exe
set GOHOSTARCH=amd64
set GOHOSTOS=windows
set GOOS=windows
set GOPATH=D:\Go\
set GORACE=
set GOROOT=D:\Programs\Go
set GOTOOLDIR=D:\Programs\Go\pkg\tool\windows_amd64
set GCCGO=gccgo
set GO386=sse2
set CC=gcc
set GOGCCFLAGS=-m32 -fmessage-length=0 -fdebug-prefix-map=C:\Users\PC\AppData\Local\Temp\go-build886287271=/tmp/go-build -gno-record-gcc-switches
set CXX=g++
set CGO_ENABLED=0
set CGO_CFLAGS=-g -O2
set CGO_CPPFLAGS=
set CGO_CXXFLAGS=-g -O2
set CGO_FFLAGS=-g -O2
set CGO_LDFLAGS=-g -O2
set PKG_CONFIG=pkg-config

Issue description

We use http.Do() method inside c.req(), and do not check for errors returned. So, it is possible to receive nil response, and got nil pointer dereference panic in line 42.
http.Do() method will return non-nil error in following cases:

1. Request is nil
2. Response missing Location header
3. Client failed to parse Location header
4. Method "request.GetBody()" returns error
5. Http.Client.Send() returns error
6. Client timeout was exceeded
   In all cases except of (5) this method returns nil as a poiner to http.Response, which will force app to panic later.

Conclusion

Taking into account the above mentioned, we need to perform error-checking for http.Do() method results.

[chripo]

Yes. It got lost.

You are a contributer and you have permission to write/push too. Don't open issues. Use this time an push your fix, even if you're not 100% shure, all things improveable!
Don't be shy. Go on.
Thanks for your report.

[chripo]

Just try to avoid merge commits. 😀

[MrVine]

@chripo, ok, thanks 😄