diff --git a/pkg/core/pcplayer/pc_player_engine.go b/pkg/core/pcplayer/pc_player_engine.go
index d877a96..909b75b 100644
--- a/pkg/core/pcplayer/pc_player_engine.go
+++ b/pkg/core/pcplayer/pc_player_engine.go
@@ -1,4 +1,4 @@
-// Package pcplayer provides megods for simple-AI logic
+// Package pcplayer provides methods for simple-AI logic
 // used in Tic-Tac-Go for calculating PC-player's move.
 package pcplayer
 
@@ -68,7 +68,7 @@ O-player lost.
 func canWinTwoMoves(gameBoard *board.Board, player letter.Letter) (result []int) {
 	// nolint:gomnd // look a scheme above - in the second one, the chain is by 2 less than max
 	minimalChainLen := gameBoard.ChainLength() - 2
-	if minimalChainLen <= 0 { // nolint:gomnd // processing this values doesn't make sense with chain smaller than 3
+	if minimalChainLen <= 0 {
 		return nil
 	}
 
@@ -92,13 +92,13 @@ validatingChains:
 	potentiallyAvailableChains := gameBoard.GetWinBoard(gameBoard.ChainLength() + 1)
 	for _, potentialPlace := range potentiallyAvailableChains {
 		for _, chain := range availableWinningChains {
-			//if potentialPlace[1] == chain[0] && potentialPlace[2] == chain[1] {
 			if reflect.DeepEqual(potentialPlace[1:len(chain)+1], chain) {
 				result = append(result, potentialPlace[len(potentialPlace)-2])
+
 				break
-				//} else if potentialPlace[2] == chain[0] && potentialPlace[3] == chain[1] {
 			} else if reflect.DeepEqual(potentialPlace[2:len(chain)+2], chain) {
 				result = append(result, potentialPlace[1])
+
 				break
 			}
 		}
diff --git a/scripts/draw-board/main.go b/scripts/draw-board/main.go
index 21ca8d7..912a612 100644
--- a/scripts/draw-board/main.go
+++ b/scripts/draw-board/main.go
@@ -1,11 +1,13 @@
 package main
 
 import (
+	"errors"
 	"flag"
 	"fmt"
-	"github.com/gucio321/tic-tac-go/pkg/core/board/letter"
 	"strconv"
 
+	"github.com/gucio321/tic-tac-go/pkg/core/board/letter"
+
 	"github.com/gucio321/tic-tac-go/pkg/core/board"
 )
 
@@ -14,6 +16,8 @@ const (
 	defaultChainLen  = 3
 )
 
+var errIncorrectLetter = errors.New("incorrect number")
+
 var _ flag.Value = &lettersValue{}
 
 type lettersValue []int
@@ -25,13 +29,13 @@ func (l *lettersValue) String() string {
 func (l *lettersValue) Set(value string) (err error) {
 	for _, letter := range value {
 		if letter < '0' || letter > '9' {
-			return fmt.Errorf("invalid letter: %v", letter)
+			return fmt.Errorf("%w %v", errIncorrectLetter, letter)
 		}
 	}
 
 	x, err := strconv.Atoi(value)
 	if err != nil {
-		return err
+		return fmt.Errorf("converting string to int: %w", err)
 	}
 
 	*l = append(*l, x)