Invalid memory address issue

[Kidd-Sisco]

Running the binary without docker and receiving this error:

[user@servername ~]$ ./prometheus-pingdom-exporter server [email protected] mypassword my_pingdom_api_key
2019/06/10 11:59:34 Listening on port 8000
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x40 pc=0x534be8]

goroutine 19 [running]:
panic(0x778b80, 0xc420010090)
/usr/local/go/src/runtime/panic.go:500 +0x1a1
github.com/russellcardullo/go-pingdom/pingdom.(*CheckService).List(0xc420106008, 0x0, 0x0, 0x0, 0x0, 0x0)
/usr/code/.gobuild/src/github.com/russellcardullo/go-pingdom/pingdom/check.go:32 +0x108
github.com/giantswarm/prometheus-pingdom-exporter/cmd.serverRun.func1(0xc4200fe120)
/usr/code/.gobuild/src/github.com/giantswarm/prometheus-pingdom-exporter/cmd/server.go:76 +0x65
created by github.com/giantswarm/prometheus-pingdom-exporter/cmd.serverRun
/usr/code/.gobuild/src/github.com/giantswarm/prometheus-pingdom-exporter/cmd/server.go:133 +0xca