What steps will reproduce the problem?

1. Download latest build of SkestakUI
2. Download latest build of another addon that uses LibClassicDurations (PallyPower, HealBot)
3. Login to game on a Paladin, select self, toggle between auras un-selecting/selecting self between auras.

What version of ShestakUI are you using? (Stating 'latest' is not useful)

latest

Do you have an error log of what happened?

Several bug reports submitted here show the error... anything relating to an 'inf' or 'infinite' errors resulting in a stack overflow.

Message: integer overflow attempting to store inf
Time: Fri Oct 18 21:19:46 2019
Count: 3145
Stack: integer overflow attempting to store inf
[C]: in function `format'
Interface\AddOns\ShestakUI\Core\Functions.lua:1399: in function <Interface\AddOns\ShestakUI\Core\Functions.lua:1396>
Interface\AddOns\ShestakUI\Core\Functions.lua:1421: in function <Interface\AddOns\ShestakUI\Core\Functions.lua:1410>

Locals: (*temporary) = "%dd"
(*temporary) = Infinite

Any additional information? (example: WoW language if not English) (Attach screenshots here if available, do not link externally)

Issue is resolved in my DEV build that has ShestakUI with an updated version of LibClassicDurations. The author of the library changed the way buffs with no expiration are handled. So other addons that use LibClassicDurations with updated versions conflict with the older version in this addon. Since LibClassicDurations is registered with ACE, the newer version supersedes the older version so some of the calls your addon makes to LibClassicDurations are getting return values from the updated functions which includes the return infinite.

change the LibClassicDurations from the latest WeakAuras toc 2.15.5 C:\Program Files (x86)\World of Warcraft_classic_\Interface\AddOns\WeakAuras\Libs\LibClassicDurations to C:\Program Files (x86)\World of Warcraft_classic_\Interface\AddOns\ShestakUI\Compatibility\Classic\Libs\LibClassicDurations
it work

All libraries have now been updated to their most current versions.