Error Handling

React 19 hands you pending state for free, and that's genuinely nice. But a finished spinner is not a finished request. AbortController is the piece almost nobody reaches for — not because it's hard, but because it looks scarier than it is. Here's the small, boring version that covers most of what you need.

Error handling is not a catch block sprinkled at the end. In a React + TanStack app, it is a product decision: what fails locally, what fails at the route level, what can retry, and what the user needs to do next.