Currently the DEV server can't recover if you export an invalid runtime
config. It ends up in a state where it stops to work but nothing is
printed to the terminal.
It now prints an error but keeps working. When building it should crash,
there's an existing test for that
https://github.com/vercel/next.js/blob/canary/test/production/exported-runtimes-value-validation/index.test.ts#L5-L17
#### Reproduce
```tsx
export default function Page() {
return <p>hello world</p>
}
export const config = {
runtime: 'something-odd',
}
```
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