Fix gosimple issues (#17179)

Signed-off-by: Mario Trangoni <mjtrangoni@gmail.com>

pkg/middleware/auth_proxy/auth_proxy.go

@@ -64,7 +64,7 @@ func newError(message string, err error) *Error {
 
 // Error returns a Error error string
 func (err *Error) Error() string {
-	return fmt.Sprintf("%s", err.Message)
+	return err.Message
 }
 
 // Options for the AuthProxy
@@ -98,20 +98,12 @@ func New(options *Options) *AuthProxy {
 func (auth *AuthProxy) IsEnabled() bool {
 
 	// Bail if the setting is not enabled
-	if !auth.enabled {
-		return false
-	}
-
-	return true
+	return auth.enabled
 }
 
 // HasHeader checks if the we have specified header
 func (auth *AuthProxy) HasHeader() bool {
-	if len(auth.header) == 0 {
-		return false
-	}
-
-	return true
+	return len(auth.header) != 0
 }
 
 // IsAllowedIP compares presented IP with the whitelist one