There are items with no search results in tab order on the Scholarly search page.
Items in tab order should be interactive in some way either because they are functional controls for the page or they contain some information that someone would be interested in. Adding items to tab order should be carefully considered to avoid causing fatigue for someone who relies on the keyboard for navigation. Refer to this W3C understanding article for more information about focus order, "W3C WAI -> Understanding SC 2.4.3: Focus Order (Level A)" -https://www.w3.org/WAI/WCAG22/Understanding/focus-order.html In this instance the search results are structured in a "feed" style interface that allows someone to rearrange the search categories to their preference. A person performing a search would likely be uninterested in categories with no results. Recommend implementing a method to prevent these items from appearing in tab order. Options could include completely removing them from focus order as there are interactive elements elsewhere on the page that could be used to inform someone about the lack of results for the category. The number of results could also be added to the heading for the category, letting someone using a screen reader know when they've reached a category with no results. Or including a method to order the categories by search results to push the categories with no results to the bottom of the stack.