[Bug] Proxyman breaks web sockets when websocket subprotocols are specified

Proxyman version

23410

macOS Version

11.5.2

Description

We're using a websocket client for graphql subscriptions from a web client.
When Proxyman is started, the web browser is unable to connect to the websocket server.

This is because the graphql subscription library that we use passes a suprotocol at connect time (namely "graphql-ws").
We've been able to isolate the issue in a very simple node server:

proxyman-ws-sample.zip

Steps to reproduce

• unzip the server
• npm install
• node ./server.js

Then

• open chrome and navigate to http://0.0.0.0:3000
• open the debug console, network tab

Result

• if Proxyman is launched, the websocket opened with the "amqp" (*) subprotocol fails, and the websocket with no suprotocol succeeds
• if Proxyman is not launched, both websockets connect successfully

(*) the subprotocol doesn't impact the result, but at least "amqp" is a well-known subprotocol from IANA registry