fix: clean up code

cmd/cmd/build/copy.go

@@ -3,6 +3,7 @@ package build
 import (
 	"fmt"
 	"io"
+	"log/slog"
 	"os"
 	"path/filepath"
 	"syscall"
@@ -74,14 +75,24 @@ func Copy(srcFile, dstFile string) error {
 		return err
 	}
 
-	defer out.Close()
+	defer func(out *os.File) {
+		err := out.Close()
+		if err != nil {
+			slog.Error("failed to close file", slog.Any("err", err))
+		}
+	}(out)
 
 	in, err := os.Open(srcFile)
 	if err != nil {
 		return err
 	}
 
-	defer in.Close()
+	defer func(in *os.File) {
+		err := in.Close()
+		if err != nil {
+			slog.Error("error closing destination file", slog.Any("err", err))
+		}
+	}(in)
 
 	_, err = io.Copy(out, in)
 	if err != nil {