Enable wastedassign linter & fix findings (#13507)

Co-authored-by: Radosław Kapka <rkapka@wp.pl>

.golangci.yml

@@ -80,7 +80,6 @@ linters:
     - thelper
     - unparam
     - varnamelen
-    - wastedassign
     - wrapcheck
     - wsl
 

beacon-chain/execution/block_reader.go

@@ -113,7 +113,7 @@ func (s *Service) BlockByTimestamp(ctx context.Context, time uint64) (*types.Hea
 	cursorNum := big.NewInt(0).SetUint64(latestBlkHeight)
 	cursorTime := latestBlkTime
 
-	numOfBlocks := uint64(0)
+	var numOfBlocks uint64
 	estimatedBlk := cursorNum.Uint64()
 	maxTimeBuffer := searchThreshold * params.BeaconConfig().SecondsPerETH1Block
 	// Terminate if we can't find an acceptable block after

beacon-chain/state/fieldtrie/field_trie.go

@@ -60,7 +60,7 @@ func NewFieldTrie(field types.FieldIndex, fieldInfo types.DataType, elements int
 	if err := validateElements(field, fieldInfo, elements, length); err != nil {
 		return nil, err
 	}
-	numOfElems := 0
+	var numOfElems int
 	if val, ok := elements.(sliceAccessor); ok {
 		numOfElems = val.Len(val.State())
 	} else {

beacon-chain/sync/rpc_status.go

@@ -210,7 +210,7 @@ func (s *Service) statusRPCHandler(ctx context.Context, msg interface{}, stream
 			"error": err,
 		}).Debug("Invalid status message from peer")
 
-		respCode := byte(0)
+		var respCode byte
 		switch err {
 		case p2ptypes.ErrGeneric:
 			respCode = responseCodeServerError

beacon-chain/sync/subscriber.go

@@ -257,7 +257,8 @@ func (s *Service) subscribeWithBase(topic string, validator wrappedVal, handle s
 func (s *Service) wrapAndReportValidation(topic string, v wrappedVal) (string, pubsub.ValidatorEx) {
 	return topic, func(ctx context.Context, pid peer.ID, msg *pubsub.Message) (res pubsub.ValidationResult) {
 		defer messagehandler.HandlePanic(ctx, msg)
-		res = pubsub.ValidationIgnore // Default: ignore any message that panics.
+		// Default: ignore any message that panics.
+		res = pubsub.ValidationIgnore // nolint:wastedassign
 		ctx, cancel := context.WithTimeout(ctx, pubsubMessageTimeout)
 		defer cancel()
 		messageReceivedCounter.WithLabelValues(topic).Inc()
@@ -781,10 +782,8 @@ func isDigestValid(digest [4]byte, genesis time.Time, genValRoot [32]byte) (bool
 }
 
 func agentString(pid peer.ID, hst host.Host) string {
-	agString := ""
-	ok := false
 	rawVersion, storeErr := hst.Peerstore().Get(pid, "AgentVersion")
-	agString, ok = rawVersion.(string)
+	agString, ok := rawVersion.(string)
 	if storeErr != nil || !ok {
 		agString = ""
 	}

container/doubly-linked-list/list.go

@@ -94,7 +94,6 @@ func (l *List[T]) Remove(n *Node[T]) {
 			n.next.prev = n.prev
 		}
 	}
-	n = nil
 	l.len--
 }
 

testing/assertions/assertions.go

@@ -52,7 +52,7 @@ func DeepEqual(loggerFn assertionLoggerFn, expected, actual interface{}, msg ...
 	if !isDeepEqual(expected, actual) {
 		errMsg := parseMsg("Values are not equal", msg...)
 		_, file, line, _ := runtime.Caller(2)
-		diff := ""
+		var diff string
 		if _, isProto := expected.(proto.Message); isProto {
 			diff = ProtobufPrettyDiff(expected, actual)
 		} else {

testing/endtoend/evaluators/execution_engine.go

@@ -83,7 +83,7 @@ func optimisticSyncEnabled(_ *types.EvaluationContext, conns ...*grpc.ClientConn
 }
 
 func retrieveHeadSlot(resp *beacon.GetBlockV2Response) (uint64, error) {
-	headSlot := uint64(0)
+	var headSlot uint64
 	var err error
 	switch resp.Version {
 	case version.String(version.Phase0):