grpc-status is not returned when making unary call

I've build a grpc server and exposed the server by envoy-proxy. I found that when grpc server throws GrpcStatusException, grpc-web always gets error saying `incomplete response` if making unary calls. I was able to get grpc-status on 'status' event if I invoke stream APIs. Please advise how to debug this issue. Thanks!

##### Version
- envoyproxy 1.17.0
- google-protobuf": "^3.15.3"
- grpc-web": "^1.2.1"

I generated protobut file by running
`protoc -I. proto/myservice.proto \
--js_out=import_style=commonjs:src --grpc-web_out=import_style=commonjs,mode=grpcweb:src
`

##### JS Code
```
var myservice = require("./my_service_pb");
var myservice_client = require("./my_service_grpc_web_pb");
var client = new myservice_client.Foo(
"http://localhost:28080"
);
var request = new myservice.BarRequest();
client.bar(request, {}, (err, response) => {
console.log(error, error)
}
```

output
```
Content.js:33 error {code: 2, message: "Incomplete response"}
```

##### envoy.yaml
```
admin:
access_log_path: /tmp/admin_access.log
address:
socket_address: { address: 0.0.0.0, port_value: 9901 }

static_resources:
listeners:
- name: main-listener
address:
socket_address: { address: 0.0.0.0, port_value: 8080 }
filter_chains:
- filters:
- name: envoy.http_connection_manager
config:
stat_prefix: ingress_http
codec_type: AUTO
route_config:
name: local_route
virtual_hosts:
- name: local_service
domains: ["*"]
routes:
- match:
prefix: "/"
route:
cluster: grpc-backend-services
max_grpc_timeout: 0s
cors:
allow_origin:
- "*"
allow_methods: GET, PUT, DELETE, POST, OPTIONS
allow_headers: keep-alive,user-agent,cache-control,content-type,content-transfer-encoding,custom-header-1,x-accept-content-transfer-encoding,x-accept-response-streaming,x-user-agent,x-grpc-web,grpc-timeout
max_age: "1728000"
expose_headers: custom-header-1,grpc-status,grpc-message
enabled: true
http_filters:
- name: envoy.grpc_web
- name: envoy.cors
- name: envoy.router
clusters:
- name: grpc-backend-services
connect_timeout: 0.25s
type: logical_dns
http2_protocol_options: {}
lb_policy: round_robin
hosts:
- socket_address:
address: localhost
port_value: 6080

```