Errors thrown in grpc method are ignored

[n0v1]

When an error is thrown in a grpc method, the grpc server will normally crash with UNCAUGHT EXCEPTION Error. When using ges, the error is ignored, the server keeps running and the call never finishes because the grpc callback isn't executed.

Example:

service.proto:

syntax = "proto3";

package dev.test;

import "google/protobuf/empty.proto";

service MyService {
  rpc test(google.protobuf.Empty) returns (google.protobuf.Empty);
}

server.js:

[...]
const server = new ExperimentalServer();

const test = (call, callback) => {
  throw new Error('Some Error');
}
server.addService(serviceDefinition, {test: test});

server.use(async (context, next) => {
  await next()
})

This happens because in the catch clause the variable handled will be true in this case (the grpc method was already called). Then the error will just be logged but the callback never executed.

node-grpc-experimental-server-interceptors/packages/grpc-experimental-server/src/index.ts

Line 112 in f01c171

if (!handled) {

I'd suggest to either never ignore errors or make sure that handled is set to true only after the original implementation was executed without throwing an error.

[edvardchen]

I knew it. I used to make this experimental feature transparent. They don't need to know its existence. Their method handlers should behave the same in both ExperimentalServer and the original grpc.Server.

When you throw error in method handler, the original grpc.Server would just make the process exit.

Now, I see the code. Since we wrap the method handler in async function, then we would throw unhandled rejection warning instead of exiting.

So I think your suggestion is reasonable. We can send the error to the client