Unary response with message and status in the trailers

[JamesNK]

I believe there is an issue in the gRPC-Web JavaScript client. When a unary response is returned with a message AND a non-OK status in the trailers then the JavaScript client assumes the call was successful. The JavaScript client assumes the call is successful because there is a message and doesn't check for a status in trailers.

The client should be updated to check for a non-OK status in trailers when processing unary calls.

[stanley-cheung]

Reference thread: grpc/grpc#12824 (comment)

[wenbozhu]

Should the message be discarded too, in this case?

I would consider such a response being generated from an ill-behaved server or is there any legit case for servers to generate the error following the response message?

[stanley-cheung]

Yes the message should be discarded if the status is non-OK, according to the link above. I can't quite actually do it though, (i.e. have a server return both a message and a non-OK status) outside of a unit-test setting. But I only tried Ruby and Node server - there seems to be no way to send both a message and a non-OK status. It may be possible for other languages though. I approached this from the unit-test perspective.