Occasional panick when closing ws connection in CLI

[Kailai-Wang]

We notice in our CI that sometimes direct_api.close().unwrap() panicks:

integritee-indirect-invocation-demo  | [2023-05-15T12:59:06Z DEBUG itc_rpc_client::ws_client] Closing connection
integritee-indirect-invocation-demo  | [2023-05-15T12:59:06Z DEBUG itc_rpc_client::ws_client] Connection is closed
integritee-indirect-invocation-demo  | [2023-05-15T12:59:06Z DEBUG integritee_cli::trusted_operation] do watch is false, closing connection
integritee-indirect-invocation-demo  | [2023-05-15T12:59:06Z DEBUG itc_rpc_client::ws_client] Web-socket close
integritee-indirect-invocation-demo  | [2023-05-15T12:59:06Z DEBUG itc_rpc_client::ws_client] Closing connection
integritee-indirect-invocation-demo  | thread 'main' panicked at 'called `Result::unwrap()` on an `Err` value: WsClientError(WS Error <Queue(Disconnected)>)', cli/src/trusted_operation.rs:245:44
integritee-indirect-invocation-demo  | note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
integritee-indirect-invocation-demo  | [2023-05-15T12:59:06Z DEBUG itc_rpc_client::ws_client] Closing connection
integritee-indirect-invocation-demo  | [2023-05-15T12:59:06Z ERROR itc_rpc_client::direct_client] Failed to close web-socket connection: WsClientError(WS Error <Queue(Disconnected)>)
Aborting on container exit...

The status was InSidechainBlock with do_watch = false.

Btw do we have any reason not returning None after the connection is closed here?

worker/cli/src/trusted_operation.rs

Line 259 in ee0e1b3

direct_api.close().unwrap();

[higherordertech]

faced same error too

[clangenb]

Hmm, if I read the code correctly, I would say that the missing return Ok(None) could actually be the reason for the panic if the worker sends something before the connection is closed on the worker side, but after we called direct_api.close().unwrap() in the client. Then, we will try to close it twice and panic.

[Kailai-Wang]

Yes it can be. It only fails sometimes though, so it can be a timing issue.

[Kailai-Wang]

So I submit a minor PR to add the missing return?

[clangenb]

Sure! Thanks a lot!