Unreadable error message being produced by the engine handler

[StephenButtolph]

We currently use %s to format messages when processing FATAL errors. However, msg never implements strings.Stringer.

• avalanchego/snow/networking/handler/handler.go

  Lines 360 to 364 in ef6a2a2

  	h.StopWithError(ctx, fmt.Errorf(
  	"%w while processing sync message: %s",
  	err,
  	msg,
  	))

• avalanchego/snow/networking/handler/handler.go

  Lines 414 to 418 in ef6a2a2

  	h.StopWithError(ctx, fmt.Errorf(
  	"%w while processing async message: %s",
  	err,
  	msg,
  	))

  • The wording here is also incorrect, it should be chan not async here.

• avalanchego/snow/networking/handler/handler.go

  Lines 742 to 746 in ef6a2a2

  	h.StopWithError(ctx, fmt.Errorf(
  	"%w while processing async message: %s",
  	err,
  	msg,
  	))