[API reference](https://evolu.dev/docs/api-reference) › [@evolu/common](https://evolu.dev/docs/api-reference/common) › [Assert](https://evolu.dev/docs/api-reference/common/Assert) › assertNonNullable

```ts
const assertNonNullable: <T>(
  value: T,
  message?: string,
) => asserts value is NonNullable<T>;
```

Defined in: [packages/common/src/Assert.ts:718](https://github.com/evoluhq/evolu/blob/ecbac001e0c18bbc45b44715f49ecc3a768c5ec9/packages/common/src/Assert.ts#L718)

Asserts that a value is non-nullable.

Following TypeScript's [NonNullable](https://www.typescriptlang.org/docs/handbook/utility-types.html#nonnullabletype), non-nullable here means neither
null nor undefined.