The second step in migrating the WebSocket observer handling to match the spec is to migrate the code for ClientImpl::Connection::websocket_handshake_error_handler() into the DefaultSocketProvider so it looks at the handshake response, converts the code to an appropriate "simulated" server error code and reports this error to the WebSocket observer using the websocket_closed_handler() function. Since these errors will be eventually reported as errors by the server, the was_clean value should be true.

Refer to the WebSocket Updates section in the technical design for details regarding these updates.

Note: websocket_error_handler() does not need to be called for these errors