all: eliminate unexported dead code

h/t to https://github.com/dominikh/go-unused

capn.go

@@ -521,5 +521,4 @@ var (
 	errCopyDepth   = errors.New("capnp: copy depth too large")
 	errOverlap     = errors.New("capnp: overlapping data on copy")
 	errListSize    = errors.New("capnp: invalid list size")
-	errObjectType  = errors.New("capnp: invalid object type")
 )

capnpc-go/capnpc-go_test.go

@@ -456,11 +456,6 @@ func containsExactlyIDs(nodes []*node, ids ...uint64) bool {
 	return true
 }
 
-func nodeString(n *node) string {
-	str, _ := text.Marshal(0xe682ab4cf923a417, n.Struct)
-	return str
-}
-
 func nodeListString(n []*node) string {
 	b := new(bytes.Buffer)
 	e := text.NewEncoder(b)

mem.go

@@ -745,15 +745,12 @@ func isInt32Bit() bool {
 }
 
 var (
-	errBufferCall         = errors.New("capnp: can't call on a memory buffer")
 	errSegmentOutOfBounds = errors.New("capnp: segment ID out of bounds")
 	errSegment32Bit       = errors.New("capnp: segment ID larger than 31 bits")
 	errMessageEmpty       = errors.New("capnp: marshalling an empty message")
 	errHasData            = errors.New("capnp: NewMessage called on arena with data")
-	errTooMuchData        = errors.New("capnp: too much data in stream")
 	errSegmentTooSmall    = errors.New("capnp: segment too small")
 	errSegmentTooLarge    = errors.New("capnp: segment too large")
-	errStreamHeader       = errors.New("capnp: invalid stream header")
 	errTooManySegments    = errors.New("capnp: too many segments to decode")
 	errDecodeLimit        = errors.New("capnp: message too large")
 )

rpc/errors.go

@@ -61,7 +61,6 @@ var (
 	errNoMainInterface = errors.New("rpc: no bootstrap interface")
 	errBadTarget       = errors.New("rpc: target not found")
 	errShutdown        = errors.New("rpc: shutdown")
-	errCallCanceled    = errors.New("rpc: call canceled")
 	errUnimplemented   = errors.New("rpc: remote used unimplemented protocol feature")
 )
 

server/server.go

@@ -225,8 +225,7 @@ type callOptionKey int
 
 // Predefined call options
 const (
-	invalidOptionKey callOptionKey = iota
-	ackSignalKey
+	ackSignalKey callOptionKey = iota + 1
 )
 
 var errClosed = errors.New("capnp: server closed")