Summary

We are currently using the parent act_page value added through the plugin. The main problem we have is that in cases where the plugin is disabled, or even potentiall removed we will get a tons of unexpected issues throughout the code.
 

Proposed solution

Here is a PoC PR with the proposed improvement as a reference.

1) Remove all the appearences of p4ge_vars

2) Consolidate the value of the parent action page only in one place.
Defining the take_action_page for both cases even if the `new_ia` is enabled|disabled

Backend

MasterBlock.php

$option_values['new_ia'] === 'on' ? $option_values['take_action_page'] : $option_values['act_page'];

 Frontend

Then, only use the take_action_page.

window.p4_vars.options.take_action_page