Subscription error: Error: Socket closed with event 1002 RSV1 set, bad opcode 7, bad MASK at Object.error

[asdutoit]

I followed the gqlgen guide on setting up graphql in a Gin project and then tried to also add support for subscriptions.
Everything works flawlessly except for subscriptions.
When testing it out in the playground, I get the following error:

Error: Socket closed with event 1002 RSV1 set, bad opcode 7, bad MASK at Object.error

I am sure I am just missing something or made a mistake in my configuration, but for the life of me, cannot see where.

I created the following graphql handler which includes the AddTransport method for subscriptions:

// graphql.go

func GraphqlHandler() gin.HandlerFunc {
	// NewExecutableSchema and Config are in the generated.go file
	// Resolver is in the resolver.go file
	h := handler.NewDefaultServer(graph.NewExecutableSchema(graph.Config{Resolvers: &graph.Resolver{}}))

	h.AddTransport(&transport.Websocket{}) // <== Added Subscription support

	return func(c *gin.Context) {
		h.ServeHTTP(c.Writer, c.Request)
	}
}

// Defining the Playground handler
func PlaygroundHandler() gin.HandlerFunc {
	h := playground.Handler("GraphQL", "/query")

	return func(c *gin.Context) {
		h.ServeHTTP(c.Writer, c.Request)
	}
}

My routes file:

// routes.go
func SetupRouter() *gin.Engine {
	r := gin.Default()
        
        // ... removed for brevity
	
	r.Any("/query", graphql.GraphqlHandler())
	r.GET("/", graphql.PlaygroundHandler())

        // ... removed for brevity

	return r
}

I would appreciate any assistance.
Many thanks!

versions

• gqlgen version: v0.17.45
• go version: go1.21.5 darwin/arm64