Currently the `fontName`-property contains an actual /Name-instance, which is a problem given that its fallback value is an empty string; seeca7f546828/src/core/default_appearance.js (L35)
The reason that this is a problem can be seen inca7f546828/src/core/primitives.js (L30-L34)
, since an empty string short-circuits the cache. Essentially, in PDF documents, a /Name-instance cannot be empty and the way that the `DefaultAppearanceEvaluator` does things is unfortunately not entirely correct. Hence the `fontName`-property is changed to instead contain a string, rather than a /Name-instance, which simplifies the code overall. *Please note:* I'm tagging this patch with "[api-minor]", since PR 12831 is included in the current pre-release (although we're not using the `fontName`-property in the display-layer).