Invalid memory adding api following guide

[lynic]

Bug Report

What did you do?
I following the guide to add memcache-operator API, but got invalid memory error:

elynn@deepin:~/Documents/source/go/src/memcached-operator$ go version
go version go1.12 linux/amd64
elynn@deepin:~/Documents/source/go/src/memcached-operator$ operator-sdk add api --api-version=cache.example.com/v1alpha1 --kind=Memcached
INFO[0000] Generating api version cache.example.com/v1alpha1 for kind Memcached. 
INFO[0000] Created pkg/apis/cache/v1alpha1/memcached_types.go 
INFO[0000] Created pkg/apis/addtoscheme_cache_v1alpha1.go 
INFO[0000] Created pkg/apis/cache/v1alpha1/register.go  
INFO[0000] Created pkg/apis/cache/v1alpha1/doc.go       
INFO[0000] Created deploy/crds/cache_v1alpha1_memcached_cr.yaml 
W0514 18:15:18.679125   15033 parse.go:224] Ignoring directory memcached-operator/pkg/apis: unable to import "memcached-operator/pkg/apis": go/build: importGo memcached-operator/pkg/apis: exit status 1
can't load package: package memcached-operator/pkg/apis: unknown import path "memcached-operator/pkg/apis": cannot find module providing package memcached-operator/pkg/apis

panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x8 pc=0xb5a1f5]

goroutine 1 [running]:
github.com/operator-framework/operator-sdk/vendor/k8s.io/gengo/parser.(*Builder).AddDirRecursive(0xc0000ccaa0, 0xc000587300, 0x1b, 0x2, 0x2)
	src/github.com/operator-framework/operator-sdk/vendor/k8s.io/gengo/parser/parse.go:229 +0xb5
github.com/operator-framework/operator-sdk/vendor/sigs.k8s.io/controller-tools/pkg/crd/generator.(*Generator).Do(0xc000901760, 0x0, 0x0)
	src/github.com/operator-framework/operator-sdk/vendor/sigs.k8s.io/controller-tools/pkg/crd/generator/generator.go:126 +0x3ac
github.com/operator-framework/operator-sdk/internal/pkg/scaffold.(*CRD).CustomRender(0xc0001f1ad0, 0x20c2ae0, 0x35cbb48, 0x7f565cbd9918, 0xc0001f1ad0, 0x1)
	src/github.com/operator-framework/operator-sdk/internal/pkg/scaffold/crd.go:122 +0x868
github.com/operator-framework/operator-sdk/internal/pkg/scaffold.(*Scaffold).doRender(0xc000901cf8, 0xc000eebb60, 0x2d, 0x0, 0x0, 0x0, 0x0, 0x0, 0xc0007b3a80, 0x12, ...)
	src/github.com/operator-framework/operator-sdk/internal/pkg/scaffold/scaffold.go:228 +0x16c
github.com/operator-framework/operator-sdk/internal/pkg/scaffold.(*Scaffold).doFile(0xc000901cf8, 0x20479e0, 0xc0001f1ad0, 0x0, 0x0)
	src/github.com/operator-framework/operator-sdk/internal/pkg/scaffold/scaffold.go:198 +0x227
github.com/operator-framework/operator-sdk/internal/pkg/scaffold.(*Scaffold).Execute(0xc000901cf8, 0xc0005d9c68, 0xc000901c98, 0x6, 0x6, 0x0, 0x0)
	src/github.com/operator-framework/operator-sdk/internal/pkg/scaffold/scaffold.go:163 +0x103
github.com/operator-framework/operator-sdk/cmd/operator-sdk/add.apiRun(0xc000336780, 0xc0000b4860, 0x0, 0x2, 0x0, 0x0)
	src/github.com/operator-framework/operator-sdk/cmd/operator-sdk/add/api.go:107 +0x4d2
github.com/operator-framework/operator-sdk/vendor/github.com/spf13/cobra.(*Command).execute(0xc000336780, 0xc0000b4820, 0x2, 0x2, 0xc000336780, 0xc0000b4820)
	src/github.com/operator-framework/operator-sdk/vendor/github.com/spf13/cobra/command.go:762 +0x465
github.com/operator-framework/operator-sdk/vendor/github.com/spf13/cobra.(*Command).ExecuteC(0xc000336000, 0x204bd80, 0xc00035d000, 0x0)
	src/github.com/operator-framework/operator-sdk/vendor/github.com/spf13/cobra/command.go:852 +0x2c0
github.com/operator-framework/operator-sdk/vendor/github.com/spf13/cobra.(*Command).Execute(...)
	src/github.com/operator-framework/operator-sdk/vendor/github.com/spf13/cobra/command.go:800
main.main()
	src/github.com/operator-framework/operator-sdk/cmd/operator-sdk/main.go:82 +0x4f7

What did you expect to see?
I pass without error

What did you see instead? Under which circumstances?
I use the operator-sdk master brach and make install to build and install.

Environment

• operator-sdk version:

elynn@deepin:~/Documents/source/go/src/memcached-operator$ operator-sdk version
operator-sdk version: v0.7.0+git

• go version:
  1.12

• Kubernetes version information:

• Kubernetes cluster kind:

• Are you writing your operator in ansible, helm, or go?
  go

Possible Solution

Additional context
Add any other context about the problem here.

[joelanford]

@lynic Thanks for reporting this issue. I think you may have found a bug in the way we determine the module path in go.mod. You can fix it yourself by editing the first line of your go.mod to be module memcached-operator, or you can recreate the project in a subdirectory within $GOPATH (e.g. $GOPATH/src/github.com/lynic/memcached-operator)

In the meantime, I'll submit a PR that fixes the bug in operator-sdk.