Add nilerr linter

.golangci.yml

@@ -98,6 +98,7 @@ linters:
     - megacheck
     - megacheck
     - misspell
+    - nilerr
     - nilnil
     - nolintlint
     - revive

dot/peerset/peerset.go

@@ -391,7 +391,7 @@ func (ps *PeerSet) allocSlots(setIdx int) error {
 
 		logger.Debugf("Sent connect message to peer %s", peerID)
 	}
-	return nil
+	return nil //nolint:nilerr
 }
 
 func (ps *PeerSet) addReservedPeers(setID int, peers ...peer.ID) error {

lib/common/types/result.go

@@ -4,6 +4,7 @@
 package types
 
 import (
+	"errors"
 	"io"
 
 	"github.com/ChainSafe/gossamer/lib/common"
@@ -53,8 +54,10 @@ func (r *Result) Decode(reader io.Reader) (*Result, error) {
 
 	for {
 		b, err := common.ReadByte(reader)
-		if err != nil {
+		if errors.Is(err, io.EOF) {
 			break
+		} else if err != nil {
+			return nil, err
 		}
 
 		r.data = append(r.data, b)

lib/genesis/test_utils.go

@@ -5,6 +5,7 @@ package genesis
 
 import (
 	"encoding/json"
+	"fmt"
 	"math/big"
 	"os"
 	"testing"
@@ -97,12 +98,12 @@ func CreateTestGenesisJSONFile(asRaw bool) (string, error) {
 
 	bz, err := json.Marshal(tGen)
 	if err != nil {
-		return "", nil
+		return "", fmt.Errorf("cannot marshal test genesis: %w", err)
 	}
 	// Write to temp file
 	_, err = file.Write(bz)
 	if err != nil {
-		return "", nil
+		return "", fmt.Errorf("cannot write JSON test genesis: %w", err)
 	}
 
 	return file.Name(), nil

lib/runtime/life/resolver.go

@@ -429,7 +429,7 @@ func storageAppend(storage runtime.Storage, key, valueToAppend []byte) error {
 		if err != nil {
 			logger.Tracef("[ext_storage_append_version_1] item in storage is not SCALE encoded, overwriting at key 0x%x", key)
 			storage.Set(key, append([]byte{4}, valueToAppend...))
-			return nil
+			return nil //nolint:nilerr
 		}
 
 		lengthBytes, err := scale.Marshal(currLength)

lib/runtime/wasmer/imports.go

@@ -1790,7 +1790,7 @@ func storageAppend(storage runtime.Storage, key, valueToAppend []byte) error {
 			logger.Tracef(
 				"[ext_storage_append_version_1] item in storage is not SCALE encoded, overwriting at key 0x%x", key)
 			storage.Set(key, append([]byte{4}, valueToAppend...))
-			return nil
+			return nil //nolint:nilerr
 		}
 
 		lengthBytes, err := scale.Marshal(currLength)

tests/utils/gossamer_utils.go

@@ -285,10 +285,11 @@ func InitNodes(num int, config string) ([]*Node, error) {
 
 // StartNodes starts given array of nodes
 func StartNodes(t *testing.T, nodes []*Node) error {
-	for _, n := range nodes {
+	for i, n := range nodes {
 		err := StartGossamer(t, n, false)
 		if err != nil {
-			return nil
+			return fmt.Errorf("node %d of %d: %w",
+				i+1, len(nodes), err)
 		}
 	}
 	return nil