Suggestion: Remove the "Add to list" button from the wrong browser windows that would lead to a crash.

[Raizanad]

This is a very very very low priority crash since it is hard for a user to even get it, and it can be easily circumvented.

On the built-in browser, certain +18 mods (labelled like that due to sensitivity of whatever kind) that require an account or you to click a button to continue saying you are fine with the content, will have an "add to list" button on the top that upon clicking it will produce a crash.

To reproduce:
Copy and paste this link (or any other like it) into the built-in browser while logged out:
https://steamcommunity.com/sharedfiles/filedetails/?id=1548995767 (This is just an example because I found hard finding a "sensitive mod" again to reproduce the issue).
You will get to a warning screen about logging, or press green button to continue.
Add to list.
Crash:

Traceback (most recent call last):
  File "E:\Games\Ludeon\RimSort\app\utils\steam\browser.py", line 190, in _add_collection_or_mod_to_list
  File "E:\Games\Ludeon\RimSort\app\utils\steam\browser.py", line 253, in _add_mod_to_list
IndexError: list index out of range

As far as I know it would be easier to make it so rimsort does not crashes at all, than it is to figure which windows have the alert of "you need to log in" going. Because the address bar is pretty much the same address as any other working mod for the "add to list" button.