all: fix issues reported by honnef.co/go/simple/cmd/gosimple

p2p/discv5/node.go

@@ -262,11 +262,8 @@ func (n NodeID) GoString() string {
 // HexID converts a hex string to a NodeID.
 // The string may be prefixed with 0x.
 func HexID(in string) (NodeID, error) {
-	if strings.HasPrefix(in, "0x") {
-		in = in[2:]
-	}
 	var id NodeID
-	b, err := hex.DecodeString(in)
+	b, err := hex.DecodeString(strings.TrimPrefix(in, "0x"))
 	if err != nil {
 		return id, err
 	} else if len(b) != len(id) {