Welcome to ESO.
Code:
"User:/AddOns/AUI/Modules/minimap/classes/PinClass.usa:16: attempt to index a nil value"
-> AddOns/AUI/ means it is in the c:\users\your windows username\documents\Elder Scrolls Online\live\AddOns\AUI folder -> so the addon which might trigger the error is AUI.
But it could be another addon like e.g. MapPins (as you said you are using this and it's also about the map. The AUI error occured at the Minimap module as the name of the lua file says in the error) as well if if interfers with AUI. Or it's a library both/one of the addons use.
Read here about how to find out what addon causes an error and how to report them properly at best:
https://www.esoui.com/forums/showthread.php?t=8858
So please navigate to the addon named in the error message and tell the author via a private message or the comments section of the addon.
Starting threads wont help to track them and fix them, it's getting very disturbing if there are several threads all about different addon errors in teh forums. The addon got a comment section or even sometimes a "bug" and "features" section where you are ale to report them.
And the addon author will be notified then and will see the comments, but he won't be notified by any threads in the forums.
The benefit for you is as well that other uers might have reported the error already, so read the comments + the 1st comment by the author (which is sometimes made sticky so it will stay at the top of the addon comments). Often you'll find ways to fix that error locally for you or a workaround to fix it until a patch is released.
Thank you.