What's the purpose of sessionLock variable in dataservice.js?

[TimeTravelersHackedMe]

Hey, I'm rebuilding this project in Ionic/Angular5 and I'm wondering what the sessionLock variable is for in this file:

https://github.com/mesh0000/poolui/blob/master/app/utils/dataservice.js

[miziel]

seems to me it is to not allow being logged in one tab if you logged out in another...
but I would consider writing or using some other session handling , as there is a known bug of unknown (for me at least) origin - if you not log out from session and open the app after longer time, it shows you're logged in but you cannot set any new values

EDIT:
btw, https://github.com/benbaran/poolui-angular is (was?) an attempt to do A5 version afaik