[CI] Add inline error check linter

app/client/keybase/keystore.go

@@ -222,7 +222,7 @@ func (keybase *badgerKeybase) GetAll() (addresses []string, keyPairs []crypto.Ke
 		defer it.Close()
 		for it.Rewind(); it.Valid(); it.Next() {
 			item := it.Item()
-			err := item.Value(func(val []byte) error {
+			if err := item.Value(func(val []byte) error {
 				b := make([]byte, len(val))
 				copy(b, val)
 
@@ -235,8 +235,7 @@ func (keybase *badgerKeybase) GetAll() (addresses []string, keyPairs []crypto.Ke
 				addresses = append(addresses, kp.GetAddressString())
 				keyPairs = append(keyPairs, kp)
 				return nil
-			})
-			if err != nil {
+			}); err != nil {
 				return err
 			}
 		}

build/linters/errs.go

@@ -0,0 +1,20 @@
+//nolint // it's not a Go code file
+//go:build !codeanalysis
+// +build !codeanalysis
+
+// This file includes our custom linters.
+// If you want to add/modify an existing linter, please check out ruleguard's documentation: https://github.com/quasilyte/go-ruleguard#documentation
+
+package gorules
+
+import (
+	"github.com/quasilyte/go-ruleguard/dsl"
+)
+
+// This is a custom linter that checks ensures a use of inline error checks
+func InlineErrCheck(m dsl.Matcher) {
+	m.Match(`$err := $x; if $err != nil { $*_ }`).
+		Where(m["err"].Type.Is(`error`)).
+		Report(`consider using inline error check: if err := $x; err != nil { $*_ }`).
+		Suggest(`if err := $x; err != nil { $*_ }`)
+}

consensus/hotstuff_replica.go

@@ -247,8 +247,7 @@ func (m *consensusModule) applyBlock(block *coreTypes.Block) error {
 	}
 
 	// Apply all the transactions in the block
-	err := utilityUnitOfWork.ApplyBlock()
-	if err != nil {
+	if err := utilityUnitOfWork.ApplyBlock(); err != nil {
 		return err
 	}
 

persistence/gov.go

@@ -168,8 +168,7 @@ func (p *PostgresContext) getParamsUpdated(height int64) ([]*coreTypes.Param, er
 	// Loop over all rows returned and load them into the ParamOrFlag struct array
 	for rows.Next() {
 		param := new(coreTypes.Param)
-		err := rows.Scan(&param.Name, &param.Value)
-		if err != nil {
+		if err := rows.Scan(&param.Name, &param.Value); err != nil {
 			return nil, err
 		}
 		param.Height = height
@@ -190,8 +189,7 @@ func (p *PostgresContext) getFlagsUpdated(height int64) ([]*coreTypes.Flag, erro
 	// Loop over all rows returned and load them into the ParamOrFlag struct array
 	for rows.Next() {
 		flag := new(coreTypes.Flag)
-		err := rows.Scan(&flag.Name, &flag.Value, &flag.Enabled)
-		if err != nil {
+		if err := rows.Scan(&flag.Name, &flag.Value, &flag.Enabled); err != nil {
 			return nil, err
 		}
 		flag.Height = height

persistence/kvstore/kvstore.go

@@ -62,8 +62,7 @@ func (store *badgerKVStore) Set(key, value []byte) error {
 	tx := store.db.NewTransaction(true)
 	defer tx.Discard()
 
-	err := tx.Set(key, value)
-	if err != nil {
+	if err := tx.Set(key, value); err != nil {
 		return err
 	}
 

shared/crypto/ed25519.go

@@ -115,8 +115,7 @@ func (priv Ed25519PrivateKey) Seed() []byte {
 
 func (priv *Ed25519PrivateKey) UnmarshalJSON(data []byte) error {
 	var privateKey string
-	err := json.Unmarshal(data, &privateKey)
-	if err != nil {
+	if err := json.Unmarshal(data, &privateKey); err != nil {
 		return err
 	}
 	return priv.UnmarshalText([]byte(privateKey))
@@ -201,8 +200,7 @@ func (pub Ed25519PublicKey) MarshalJSON() ([]byte, error) {
 
 func (pub *Ed25519PublicKey) UnmarshalJSON(data []byte) error {
 	var publicKey string
-	err := json.Unmarshal(data, &publicKey)
-	if err != nil {
+	if err := json.Unmarshal(data, &publicKey); err != nil {
 		return err
 	}
 	keyBytes, err := hex.DecodeString(publicKey)

shared/crypto/keys.go

@@ -32,8 +32,7 @@ type PrivateKey interface {
 
 func (a *Address) UnmarshalJSON(data []byte) error {
 	var address string
-	err := json.Unmarshal(data, &address)
-	if err != nil {
+	if err := json.Unmarshal(data, &address); err != nil {
 		return err
 	}
 	bz, err := hex.DecodeString(address)