chore(dot): remove unneeded error functions

dot/core/errors.go

@@ -46,18 +46,3 @@ var (
 
 	errNilCodeSubstitutedState = errors.New("cannot have nil CodeSubstitutedStat")
 )
-
-// ErrNilChannel is returned if a channel is nil
-func ErrNilChannel(s string) error {
-	return fmt.Errorf("cannot have nil channel %s", s)
-}
-
-// ErrMessageCast is returned if unable to cast a network.Message to a type
-func ErrMessageCast(s string) error {
-	return fmt.Errorf("could not cast network.Message to %s", s)
-}
-
-// ErrUnsupportedMsgType is returned if we receive an unknown message type
-func ErrUnsupportedMsgType(d byte) error {
-	return fmt.Errorf("received unsupported message type %d", d)
-}

dot/sync/errors.go

@@ -48,8 +48,3 @@ var (
 	errStartAndEndMismatch          = errors.New("request start and end hash are not on the same chain")
 	errFailedToGetDescendant        = errors.New("failed to find descendant block")
 )
-
-// ErrNilChannel is returned if a channel is nil
-func ErrNilChannel(s string) error {
-	return fmt.Errorf("cannot have nil channel %s", s)
-}