[BUG] Should change to Email

[jiaohu]

The function to check user exist use the wrong param.

chat/internal/rpc/chat/user.go

Lines 419 to 421 in d8787b2

	if req.User.Email != "" {
	account, err := o.Database.TakeCredentialByAccount(ctx, req.User.AreaCode)
	if err != nil && !errors.Is(err, mongo.ErrNoDocuments) {