lnwire: eliminate the ErrorCode field within the Error message

This commit does away with the ErrorCode field in order to ensure that
we’re properly compatible with BOLT-0002. In the future the error code
field may be re-introduced as it’s much easier to check against an
internet error rather than interpret a byte slice describing the error.

lnwire/error.go

@@ -8,12 +8,12 @@ import (
 
 // ErrorCode represents the short error code for each of the defined errors
 // within the Lightning Network protocol spec.
-type ErrorCode uint16
+type ErrorCode uint8
 
 // ToGrpcCode is used to generate gRPC specific code which will be propagated
 // to the ln rpc client. This code is used to have more detailed view of what
-// goes wrong and also in order to have the ability pragmatically determine
+// goes wrong and also in order to have the ability pragmatically determine the
-// the error and take specific actions on the client side.
+// error and take specific actions on the client side.
 func (e ErrorCode) ToGrpcCode() codes.Code {
 	return (codes.Code)(e) + 100
 }
@@ -28,12 +28,26 @@ const (
 	// latest state of the blockchain.
 	ErrSynchronizingChain ErrorCode = 2
 
-	// ErrChanTooLarge is retruend by a remote peer that receives a
+	// ErrChanTooLarge is returned by a remote peer that receives a
 	// FundingOpen request for a channel that is above their current
 	// soft-limit.
 	ErrChanTooLarge ErrorCode = 3
 )
 
+// String returns a human readable version of the target ErrorCode.
+func (e ErrorCode) String() string {
+	switch e {
+	case ErrMaxPendingChannels:
+		return "Number of pending channels exceed maximum"
+	case ErrSynchronizingChain:
+		return "Synchronizing blockchain"
+	case ErrChanTooLarge:
+		return "channel too large"
+	default:
+		return "unknown error"
+	}
+}
+
 // ErrorData is a set of bytes associated with a particular sent error. A
 // receiving node SHOULD only print out data verbatim if the string is composed
 // solely of printable ASCII characters. For reference, the printable character
@@ -52,13 +66,6 @@ type Error struct {
 	// entire established connection.
 	ChanID ChannelID
 
-	// Code is the short error code that succinctly identifies the error
-	// code. This is similar field is similar to HTTP error codes.
-	//
-	// TODO(roasbeef): make PR to repo to add error codes, in addition to
-	// what's there atm
-	Code ErrorCode
-
 	// Data is the attached error data that describes the exact failure
 	// which caused the error message to be sent.
 	Data ErrorData
@@ -80,7 +87,6 @@ var _ Message = (*Error)(nil)
 func (c *Error) Decode(r io.Reader, pver uint32) error {
 	return readElements(r,
 		&c.ChanID,
-		&c.Code,
 		&c.Data,
 	)
 }
@@ -92,7 +98,6 @@ func (c *Error) Decode(r io.Reader, pver uint32) error {
 func (c *Error) Encode(w io.Writer, pver uint32) error {
 	return writeElements(w,
 		c.ChanID,
-		c.Code,
 		c.Data,
 	)
 }