What Does 'opcode -1' Mean In Chrome?

I'm using Chrome browser and I'm trying to create a WebSocket connection (using javascript) but sometimes I get an error. When I'm looking in Developer Tools for the WS connection,

Solution 1:

WebSocket OPCODEs describe how to interpret the frame. The OPCODES are formally between 0-10, OPCODE -1 says "not frame that can be used":

https://developer.mozilla.org/en-US/docs/Web/API/WebSockets_API/Writing_WebSocket_servers#Exchanging_Data_Frames

https://tools.ietf.org/id/draft-ietf-hybi-thewebsocketprotocol-09.html#rfc.section.11.14