kustomize cfg grep with no arguments causes panic

[paololazzari]

$ kustomize cfg grep 
panic: runtime error: index out of range [0] with length 0

goroutine 1 [running]:
sigs.k8s.io/kustomize/cmd/config/internal/commands.(*GrepRunner).preRunE(0xd?, 0x0?, {0x101adc1a0?, 0x100e93c6c?, 0x14000179d00?})
    /home/runner/work/kustomize/kustomize/cmd/config/internal/commands/grep.go:69 +0x3cc
github.com/spf13/cobra.(*Command).execute(0x1400027ac00, {0x101adc1a0, 0x0, 0x0})
    /home/runner/go/pkg/mod/github.com/spf13/cobra@v1.8.0/command.go:968 +0x7e8
github.com/spf13/cobra.(*Command).ExecuteC(0x14000183500)
    /home/runner/go/pkg/mod/github.com/spf13/cobra@v1.8.0/command.go:1115 +0x344
github.com/spf13/cobra.(*Command).Execute(0x1019f1888?)
    /home/runner/go/pkg/mod/github.com/spf13/cobra@v1.8.0/command.go:1039 +0x1c
main.main()
    /home/runner/work/kustomize/kustomize/kustomize/main.go:14 +0x20

Kustomize version

v5.4.1

Operating system

MacOS

[yeedove]

/assign

[stormqueen1990]

/triage accepted