The link is not displayed when str is blank in admin.

[Antoliny]

In the admin page, there are parts where the model's __str__ value is used, providing links that allow navigation to the object when the value is clicked.
However, when __str__ is blank, while it’s not an issue for the value to appear as blank, the <a> tag's innerHTML being empty prevents the layout from being displayed on the screen, and it also cannot function as a link.

While it’s very rare for a user to assign a blank value to __str__, I still believe that it should at least function as a link.
Just like with fields, when the value is blank, a default value such as "-" should be used to ensure that it can at least function as a link.

[Sarah Boyce]

Similar nature to #36114
It will be difficult to find all of these but we can try 👍

[Antoliny]

I have confirmed that this issue also occurs in the breadcrumb. Additionally, while a message can still function as a link even when it is blank, it may need to be changed for consistency, so I have added that.

[Antoliny]

​PR

[Raphael Gaschignard]

I do not know how appropriate it would be as a solution, but specifically for layout collapse it is possible with CSS to detect empty anchor tags and then add a *touch* of content:

a:empty::after {
  /* insert two non-blocking spaces, making the link appear */
  content: '\00A0\00A0';
}

The point here being that there could be some fallback in the admin in particular for this issue (that feels pretty easy to accidentally do when not careful with str). Could even put in text like "(blank)". But then we're looking at translation strings in CSS...