Error when using newspaper

When trying to use newspaper with the line newspaper https://www.theguardian.com/us-news/2017/jul/11/donald-trump-jr-email-chain-russia-hillary-clinton I get the following error:

panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x40 pc=0x6306b6]

goroutine 1 [running]:
main.main()
    /home/nrfrd/.go/src/github.com/desmondhume/newspaper/main.go:39 +0x2b6

I'm running Arch Linux using zsh and I added my api key in my .zsh file this way : export MERCURY_API_KEY="mykeytakenfrommercuryswebpage"

该提问来源于开源项目：desmondhume/newspaper