Why is my `fetch` call not throwing on a 404 or 500 response?

Question

```js
try {
  const res = await fetch('/api/user/999');
  const data = await res.json();
} catch (e) {
  console.log('error');
}
```

The endpoint returns 404 but my `catch` never runs. Then `res.json()` fails with a confusing error.

Accepted Answer

`fetch` only rejects on **network failures** (DNS error, offline, CORS block). Any HTTP response, including 404 and 500, is a *successful* fetch. You have to check `res.ok` yourself:

```js
async function getJson(url) {
  const res = await fetch(url);
  if (!res.ok) {
    const text = await res.text();
    throw new Error(`HTTP ${res.status}: ${text.slice(0, 200)}`);
  }
  return res.json();
}
```

Wrap this once and use it everywhere. The `res.json()` error you see is because the 404 body is HTML or empty, not JSON.

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