coder external-auth access-token panic when no provider name is given

[matifali]

coder@test:~$ coder external-auth access-token
panic: runtime error: index out of range [0] with length 0

goroutine 1 [running]:
github.com/coder/coder/v2/cli.(*RootCmd).externalAuthAccessToken.func1(0xc00068c200)
        /home/runner/actions-runner/_work/coder/coder/cli/externalauth.go:75 +0x778
github.com/coder/coder/v2/cli.(*RootCmd).Command.func6.1(0x0?)
        /home/runner/actions-runner/_work/coder/coder/cli/root.go:282 +0xd1
github.com/coder/coder/v2/cli/clibase.(*Invocation).run(0xc00068c200, 0xc00059be00)
        /home/runner/actions-runner/_work/coder/coder/cli/clibase/cmd.go:388 +0x10b2
github.com/coder/coder/v2/cli/clibase.(*Invocation).run(0xc00068c000, 0xc00059be00)
        /home/runner/actions-runner/_work/coder/coder/cli/clibase/cmd.go:325 +0xb5e
github.com/coder/coder/v2/cli/clibase.(*Invocation).run(0xc00068c000, 0xc00059be00)
        /home/runner/actions-runner/_work/coder/coder/cli/clibase/cmd.go:325 +0xb5e
github.com/coder/coder/v2/cli/clibase.(*Invocation).Run(0xc00059beb8?)
        /home/runner/actions-runner/_work/coder/coder/cli/clibase/cmd.go:478 +0xe5
github.com/coder/coder/v2/cli.(*RootCmd).RunMain(0xc000225400, {0xc000626000, 0x26, 0x40})
        /home/runner/actions-runner/_work/coder/coder/cli/root.go:137 +0x1aa
main.main()
        /home/runner/actions-runner/_work/coder/coder/enterprise/cmd/coder/main.go:11 +0x45