Start wrapping errors.

helpers.go

@@ -28,22 +28,22 @@ func validUTF8(s string) string {
 func validURI(s string) (*url.URL, error) {
 	// Check if URI is valid
 	uri, err := url.ParseRequestURI(s)
-	return uri, err
+	return uri, fmt.Errorf("validURI: %w", err)
 }
 
 func readFile(path string) (*bytes.Buffer, error) {
 	file, err := os.Open(path)
 	if err != nil {
-		return nil, err
+		return nil, fmt.Errorf("readFile: %w", err)
 	}
 	buffer := new(bytes.Buffer)
 	_, err = buffer.ReadFrom(file)
 	if err != nil {
-		return nil, err
+		return nil, fmt.Errorf("readFile: %w", err)
 	}
 	err = file.Close()
 	if err != nil {
-		fmt.Println(" error while closing file:", err)
+		fmt.Println("error while closing file:", err)
 	}
 	return buffer, nil
 }

main.go

@@ -7,6 +7,7 @@ package main
 import (
 	"bufio"
 	"crypto/tls"
+	"errors"
 	"fmt"
 	"io"
 	"log"
@@ -38,13 +39,13 @@ func readMessage(messageFilePath string) (string, error) {
 	// Check that message file is existing.
 	_, err = os.Stat(messageFilePath)
 	if os.IsNotExist(err) {
-		return output, err
+		return output, fmt.Errorf("readMessage: %w", err)
 	}
 
 	// Open message file.
 	file, err := os.Open(messageFilePath)
 	if err != nil {
-		return output, err
+		return output, fmt.Errorf("readMessage: %w", err)
 	}
 	scanner := bufio.NewScanner(file)
 	scanner.Split(bufio.ScanLines)
@@ -56,9 +57,9 @@ func readMessage(messageFilePath string) (string, error) {
 		}
 	}
 
-	if err := scanner.Err(); err != nil {
+	if err := scanner.Err(); errors.Unwrap(err) != nil {
 		if err != io.EOF {
-			return "", err
+			return "", fmt.Errorf("readMessage: %w", err)
 		}
 	}
 
@@ -67,7 +68,7 @@ func readMessage(messageFilePath string) (string, error) {
 		fmt.Println("error while closing file:", err)
 	}
 
-	return output, err
+	return output, fmt.Errorf("readMessage: %w", err)
 }
 
 func main() {