deploying compact 3-nodes cluster on GCP, by setting mastersSchedulable as true and removing worker machineset YAMLs, got panic

$ openshift-install version
openshift-install 4.13.0-0.nightly-2022-12-04-194803
built from commit cc689a21044a76020b82902056c55d2002e454bd
release image registry.ci.openshift.org/ocp/release@sha256:9e61cdf7bd13b758343a3ba762cdea301f9b687737d77ef912c6788cbd6a67ea
release architecture amd64

Always

1. create manifests
2. set 'spec.mastersSchedulable' as 'true', in <installation dir>/manifests/cluster-scheduler-02-config.yml
3. remove the worker machineset YAML file from <installation dir>/openshift directory
4. create cluster 

Got "panic: runtime error: index out of range [0] with length 0".

The installation should succeed, or giving clear error messages. 

$ openshift-install version
openshift-install 4.13.0-0.nightly-2022-12-04-194803
built from commit cc689a21044a76020b82902056c55d2002e454bd
release image registry.ci.openshift.org/ocp/release@sha256:9e61cdf7bd13b758343a3ba762cdea301f9b687737d77ef912c6788cbd6a67ea
release architecture amd64
$ 
$ openshift-install create manifests --dir test1
? SSH Public Key /home/fedora/.ssh/openshift-qe.pub
? Platform gcp
INFO Credentials loaded from file "/home/fedora/.gcp/osServiceAccount.json"
? Project ID OpenShift QE (openshift-qe)
? Region us-central1
? Base Domain qe.gcp.devcluster.openshift.com
? Cluster Name jiwei-1205a
? Pull Secret [? for help] ******
INFO Manifests created in: test1/manifests and test1/openshift 
$ 
$ vim test1/manifests/cluster-scheduler-02-config.yml
$ yq-3.3.0 r test1/manifests/cluster-scheduler-02-config.yml spec.mastersSchedulable
true
$ 
$ rm -f test1/openshift/99_openshift-cluster-api_worker-machineset-?.yaml
$ 
$ tree test1
test1
├── manifests
│   ├── cloud-controller-uid-config.yml
│   ├── cloud-provider-config.yaml
│   ├── cluster-config.yaml
│   ├── cluster-dns-02-config.yml
│   ├── cluster-infrastructure-02-config.yml
│   ├── cluster-ingress-02-config.yml
│   ├── cluster-network-01-crd.yml
│   ├── cluster-network-02-config.yml
│   ├── cluster-proxy-01-config.yaml
│   ├── cluster-scheduler-02-config.yml
│   ├── cvo-overrides.yaml
│   ├── kube-cloud-config.yaml
│   ├── kube-system-configmap-root-ca.yaml
│   ├── machine-config-server-tls-secret.yaml
│   └── openshift-config-secret-pull-secret.yaml
└── openshift
    ├── 99_cloud-creds-secret.yaml
    ├── 99_kubeadmin-password-secret.yaml
    ├── 99_openshift-cluster-api_master-machines-0.yaml
    ├── 99_openshift-cluster-api_master-machines-1.yaml
    ├── 99_openshift-cluster-api_master-machines-2.yaml
    ├── 99_openshift-cluster-api_master-user-data-secret.yaml
    ├── 99_openshift-cluster-api_worker-user-data-secret.yaml
    ├── 99_openshift-machineconfig_99-master-ssh.yaml
    ├── 99_openshift-machineconfig_99-worker-ssh.yaml
    ├── 99_role-cloud-creds-secret-reader.yaml
    └── openshift-install-manifests.yaml2 directories, 26 files
$ 
$ openshift-install create cluster --dir test1
INFO Consuming Openshift Manifests from target directory
INFO Consuming Master Machines from target directory 
INFO Consuming Worker Machines from target directory 
INFO Consuming OpenShift Install (Manifests) from target directory 
INFO Consuming Common Manifests from target directory 
INFO Credentials loaded from file "/home/fedora/.gcp/osServiceAccount.json" 
panic: runtime error: index out of range [0] with length 0goroutine 1 [running]:
github.com/openshift/installer/pkg/tfvars/gcp.TFVars({{{0xc000cf6a40, 0xc}, {0x0, 0x0}, {0xc0011d4a80, 0x91d}}, 0x1, 0x1, {0xc0010abda0, 0x58}, ...})
        /go/src/github.com/openshift/installer/pkg/tfvars/gcp/gcp.go:70 +0x66f
github.com/openshift/installer/pkg/asset/cluster.(*TerraformVariables).Generate(0x1daff070, 0xc000cef530?)
        /go/src/github.com/openshift/installer/pkg/asset/cluster/tfvars.go:479 +0x6bf8
github.com/openshift/installer/pkg/asset/store.(*storeImpl).fetch(0xc000c78870, {0x1a777f40, 0x1daff070}, {0x0, 0x0})
        /go/src/github.com/openshift/installer/pkg/asset/store/store.go:226 +0x5fa
github.com/openshift/installer/pkg/asset/store.(*storeImpl).Fetch(0x7ffc4c21413b?, {0x1a777f40, 0x1daff070}, {0x1dadc7e0, 0x8, 0x8})
        /go/src/github.com/openshift/installer/pkg/asset/store/store.go:76 +0x48
main.runTargetCmd.func1({0x7ffc4c21413b, 0x5})
        /go/src/github.com/openshift/installer/cmd/openshift-install/create.go:259 +0x125
main.runTargetCmd.func2(0x1dae27a0?, {0xc000c702c0?, 0x2?, 0x2?})
        /go/src/github.com/openshift/installer/cmd/openshift-install/create.go:289 +0xe7
github.com/spf13/cobra.(*Command).execute(0x1dae27a0, {0xc000c70280, 0x2, 0x2})
        /go/src/github.com/openshift/installer/vendor/github.com/spf13/cobra/command.go:876 +0x67b
github.com/spf13/cobra.(*Command).ExecuteC(0xc000c3a500)
        /go/src/github.com/openshift/installer/vendor/github.com/spf13/cobra/command.go:990 +0x3bd
github.com/spf13/cobra.(*Command).Execute(...)
        /go/src/github.com/openshift/installer/vendor/github.com/spf13/cobra/command.go:918
main.installerMain()
        /go/src/github.com/openshift/installer/cmd/openshift-install/main.go:61 +0x2b0
main.main()
        /go/src/github.com/openshift/installer/cmd/openshift-install/main.go:38 +0xff
$