Bug with --lb-startegy flag

[sunoce]

Command line arguments / config
ghz localhost:6565 --proto proto-files/service.proto --data-file request-data-files/test_data.json --lb-strategy=round_robin

Describe the bug
Hello guys,

I wanted to test the '--lb-strategy' flag that was introduced in release v0.91.0.
When I use this flag in the cmd command, I get the following error the newest release:

panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x7a1d7e]

goroutine 1 [running]:
go.uber.org/zap.(*SugaredLogger).log(0x0, 0x1, 0x0, 0x0, 0xc00072d9e8, 0x3, 0x3, 0x0, 0x0, 0x0)
/home/runner/go/pkg/mod/go.uber.org/[email protected]/sugar.go:221 +0x17e
go.uber.org/zap.(*SugaredLogger).Warn(...)
/home/runner/go/pkg/mod/go.uber.org/[email protected]/sugar.go:107
main.main()
/home/runner/work/ghz/ghz/cmd/ghz/main.go:319 +0xaed

To check if this is only a bug i downloaded release v0.91.0 and tested the same call with this release without an error.

Expected behavior
No error while using lb-strategy

Environment

• OS: Ubuntu