Building a Error Library

Error handling is one of those things that quietly shapes the entire experience of a system. When it works well, users recover quickly, support teams stay efficient, and developers can focus on real problems. When it doesn’t, even small issues turn into long, frustrating investigations. To improve this, it helps to start with a simple question: what do we actually want from our errors? A big part of the problem with many existing approaches is that they treat all errors more or less the same. In practice, though, not all errors are equal. There’s an important difference between something the client did wrong and something that failed inside the system—and that difference should shape how we handle them. When a client makes a mistake—bad input, incorrect API usage, missing data—the system should make it obvious what went wrong and how to fix it. That means returning clear, human-readable messages, along with structured error codes for programmatic use. It also means logging enough conte