fix(handlers): align response status codes for the verify endpoint (#2016)

This aligns all response status codes on the /api/verify endpoint when an error occurs, making it impossible to determine the actual reason for the failure.

internal/handlers/handler_verify.go

@@ -428,7 +428,9 @@ func VerifyGet(cfg schema.AuthenticationBackendConfiguration) middlewares.Reques
 		targetURL, err := ctx.GetOriginalURL()
 
 		if err != nil {
-			ctx.Error(fmt.Errorf("Unable to parse target URL: %s", err), operationFailedMessage)
+			ctx.Logger.Error(fmt.Errorf("Unable to parse target URL: %s", err))
+			ctx.ReplyUnauthorized()
+
 			return
 		}