---
title: Errors and warnings
description: Every Ilha error and warning carries a stable ILHA code, a fix hint, and a docs link.
---

Ilha reports problems with a stable code. Each message follows one shape, so you and your tools can match on the code instead of the wording:

```txt
[ILHA001] <what went wrong>. Fix: <what to do> See https://ilha.build/errors/ILHA001
```

Errors are `IlhaError` instances. They expose `code`, `fix`, and `docs`:

```tsx twoslash
import { IlhaError, atom } from "ilha";

try {
  atom(0);
} catch (error) {
  if (error instanceof IlhaError) {
    console.log(error.code, error.fix, error.docs);
  }
}
```

Warnings go through `console.warn` with the same message shape. Ilha shows each warning once per code and detail.

| Code | Kind | Meaning |
| --- | --- | --- |
| [ILHA001](/errors/ILHA001) | error | A primitive ran with no active component |
| [ILHA002](/errors/ILHA002) | warning | The atom/watch slot count changed between renders |
| [ILHA003](/errors/ILHA003) | error | An atom handle was used from a different island |
| [ILHA004](/errors/ILHA004) | error | A generator resumed while an instruction was running |
| [ILHA005](/errors/ILHA005) | warning | Two sibling components share a key |
| [ILHA006](/errors/ILHA006) | warning | Hydration found different markup and fully remounted |
| [ILHA007](/errors/ILHA007) | error | `renderToString` found unsafe raw text in a tag |