put IsNil in utils package

adapters/p2p2core/felt.go

@@ -2,10 +2,10 @@ package p2p2core
 
 import (
 	"encoding/binary"
-	"reflect"
 
 	"github.com/NethermindEth/juno/core/felt"
 	"github.com/NethermindEth/juno/p2p/starknet/spec"
+	"github.com/NethermindEth/juno/utils"
 	"github.com/ethereum/go-ethereum/common"
 )
 
@@ -28,7 +28,7 @@ func AdaptFelt(f *spec.Felt252) *felt.Felt {
 func adapt(v interface{ GetElements() []byte }) *felt.Felt {
 	// when passing a nil pointer `v` is boxed to an interface and is not nil
 	// see: https://blog.devtrovert.com/p/go-secret-interface-nil-is-not-nil
-	if v == nil || reflect.ValueOf(v).IsNil() {
+	if utils.IsNil(v) {
 		return nil
 	}
 

jsonrpc/server.go

@@ -422,12 +422,8 @@ func isBatch(reader *bufio.Reader) bool {
 	return false
 }
 
-func isNil(i any) bool {
-	return i == nil || reflect.ValueOf(i).IsNil()
-}
-
 func isNilOrEmpty(i any) (bool, error) {
-	if isNil(i) {
+	if utils.IsNil(i) {
 		return true, nil
 	}
 
@@ -484,7 +480,7 @@ func (s *Server) handleRequest(ctx context.Context, req *Request) (*response, ht
 		header = (tuple[1].Interface()).(http.Header)
 	}
 
-	if errAny := tuple[errorIndex].Interface(); !isNil(errAny) {
+	if errAny := tuple[errorIndex].Interface(); !utils.IsNil(errAny) {
 		res.Error = errAny.(*Error)
 		if res.Error.Code == InternalError {
 			s.listener.OnRequestFailed(req.Method, res.Error)

utils/check.go

@@ -0,0 +1,7 @@
+package utils
+
+import "reflect"
+
+func IsNil(i any) bool {
+	return i == nil || reflect.ValueOf(i).IsNil()
+}