Craig Dennis reminds designers that good design must always consider the full user experience, not just the happy path:
Empty states are places in apps that have no content or data. They are empty. A blank page. Traditionally empty states are overlooked as most designers focus on how best to display lots of content or data. It’s common for empty states to be dealt with by developers as they are often caused by exceptions (such as no internet connection). They often write the copy and as a result it can be a little difficult to understand or it is left with the basic styles. Not the best combination. It should be logged as something that needs designing but that doesn’t always happen.
While Craig focuses on empty states in this article there are many other edge cases to consider. It is a good idea to go make edge case analysis a part of your regular design process. It's also a good idea to request that developers discuss any new edge cases you hadn't considered with you. Every aspect of the user experience should be designed with intention.