Use errors.New if the message is constant

sshmux.go

@@ -3,6 +3,7 @@ package main
 import (
 	"context"
 	"encoding/base64"
+	"errors"
 	"fmt"
 	"io"
 	"log"
@@ -42,10 +43,10 @@ type upstreamInformation struct {
 
 func validateKey(config SSHKeyConfig) (ssh.Signer, error) {
 	if config.Path == "" && config.Base64 == "" && config.Content == "" {
-		return nil, fmt.Errorf("one of path, base64 or content of the SSH key must be set")
+		return nil, errors.New("one of path, base64 or content of the SSH key must be set")
 	}
 	if (config.Path != "" && config.Base64 != "") || (config.Path != "" && config.Content != "") || (config.Base64 != "" && config.Content != "") {
-		return nil, fmt.Errorf("only one of path, base64 or content of the SSH key can be set")
+		return nil, errors.New("only one of path, base64 or content of the SSH key can be set")
 	}
 	var pemFile []byte
 	if config.Path != "" {
@@ -265,7 +266,7 @@ auth_requests:
 						return err
 					}
 					if len(answers) != len(questions) {
-						return fmt.Errorf("ssh: numbers of answers and questions do not match")
+						return errors.New("ssh: numbers of answers and questions do not match")
 					}
 					if req.Payload == nil {
 						req.Payload = make(map[string]string, len(challenge.Fields))