nil-pointer error when adding service-registry artifact role

[craicoverflow]

Description

Version: dev

When adding a role to a service-registry, if I do not provide the role value then I get a nil-pointer error.

Steps to reproduce

$ rhoas service-registry role add --username ephelan_kafka_devexp
Updating role for principal
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0xad221b]

goroutine 1 [running]:
github.com/redhat-developer/app-services-cli/pkg/cmd/registry/artifact/role/add.runAdd(0xc0000e0a00, 0xc0000bdd90, 0x0)
        /home/ephelan/code/github.com/redhat-developer/app-services-cli/pkg/cmd/registry/artifact/role/add/add.go:126 +0x2bb
github.com/redhat-developer/app-services-cli/pkg/cmd/registry/artifact/role/add.NewAddCommand.func1(0xc0000dd180, 0xc000557840, 0x0, 0x2, 0x0, 0x0)
        /home/ephelan/code/github.com/redhat-developer/app-services-cli/pkg/cmd/registry/artifact/role/add/add.go:93 +0xe5
github.com/spf13/cobra.(*Command).execute(0xc0000dd180, 0xc000557820, 0x2, 0x2, 0xc0000dd180, 0xc000557820)
        /home/ephelan/.gvm/pkgsets/go1.16.4/global/pkg/mod/github.com/spf13/[email protected]/command.go:856 +0x472
github.com/spf13/cobra.(*Command).ExecuteC(0xc000369680, 0x2013038, 0x3, 0xc000369680)
        /home/ephelan/.gvm/pkgsets/go1.16.4/global/pkg/mod/github.com/spf13/[email protected]/command.go:974 +0x375
github.com/spf13/cobra.(*Command).Execute(...)
        /home/ephelan/.gvm/pkgsets/go1.16.4/global/pkg/mod/github.com/spf13/[email protected]/command.go:902
main.main()
        /home/ephelan/code/github.com/redhat-developer/app-services-cli/cmd/rhoas/main.go:52 +0x2aa