The MSG_TYPE_ERROR (cloud_type=9) arm previously logged only the payload
byte count, so when Qobuz cloud rejected a session (zombie session,
conflicting device, expired JWT, ...) we had no signal beyond an opaque
"bytes=13" TransportError. That hid the actual cause of the 2s flicker
loop seen after the app sat minimized for 1-2 hours (issue #358).
The qws.proto ErrorMessage (messageTypeId=9) carries:
uint32 msg_id = 1
uint64 msg_date = 2
uint32 code = 3
string descr = 4
Decode it via a local QwsErrorMessage prost struct, log a warn line with
the decoded code+descr, and emit a new TransportEvent::CloudError so
qconnect-app and qconnect_service can react. qconnect_service forwards
it as a "qconnect:cloud_error" diagnostic (level=warning) and logs it.
qconnect-app treats it as a no-op forwarder for now, matching the
existing pattern for other transport-only events. Decode failures fall
back to the previous TransportError path under a distinct stage name so
they are still visible.
Adds a tokio test that builds a real MSG_TYPE_ERROR frame and asserts
the transport emits CloudError (not the legacy TransportError).
Refs #358
cc
vicrodh
d74332514d