grpc-js: end event emitted on client streaming errors

### Problem description
If an uncaught error occurs in the data handler the end handler is still fired. I'm not sure if this is intentional but based on the standard node.js readable stream I would expect this not to be called.

In this scenario because the callback is already handled [here](https://github.com/grpc/grpc-node/blob/%40grpc/grpc-js%401.0.3/packages/grpc-js/src/server.ts#L644) you cannot subscribe to the error event to handle the error and send a response.
```
clientStreamExample(call, callback) {
call.on('data', () => {
throw new Error('my error');
});

call.on('end', () => {
console.log('ended');
callback(null, {});
});
}
```

### Environment
- OS name, version and architecture: macOS 10.15.4
- Node version: v12.16.2
- Package name and version @grpc/grpc-js@1.0.3