Update readme.md

Author: RoyalIcing

readme.md

@@ -16,7 +16,14 @@
 - States can be reused.
 - Nest machines inside one another.
 - Use native JavaScript features such as Promise, AbortSignal, and EventTarget.
-- Conform various stateful things such as offline status, promises, fetch, IntersectionObserver, ResizeObserver. Manage these things in a consistent way with a consistent interface.
+- Conform various stateful things such as offline status, promises, fetch, IntersectionObserver, ResizeObserver, window.location. Manage these things in a consistent way with a consistent interface.
+
+### Problems
+
++ Making sure my code is 100% robust and doesn't fall into inconsistent states is hard.
+- It's easy to forget about error handling.
+- Built-in browser features (such as InteractionObserver) are powerful but a pain to manage correctly.
+- Managing various flavors of state is hard: the current URL, local storage, focused element, fetch response, caches, offline/online.
 
 ## Install