Guidebook: Error message mentions discontinued Google Plus service

iOS 13.3.1
Guidebook app for iOS (version 7.13.1)
Date: 03/09/20

Description:

Error messaging problem with the Guidebook app for iOS. An error message in the app says, "Error authenticating with Google+"

This is confusing, as Google discontinued the Google+ service a long time ago. Here is the error message:

Steps to Reproduce:

1. Download and launch the Guidebook app for iOS
2. Skip the tutorial
3. Select the profile option in upper right
4. From the bottom of the screen, under "More Ways to Sign up" choose the Google option
5. From the ""Guidebook" wants to use "google.com" to Sign In" pop-up select "Cancel"

Result: The error message from canceling out of a google sign-in says: "Error authenticating with Google+"

Expected: This error message should be changed, as Google discontinued Google+ a long time ago!