---
url: https://node-ts.github.io/bus/api/bus-core/functions/assertUnreachable.md
---
[API reference](../../index.md) / [@node-ts/bus-core](../index.md) / assertUnreachable

# Function: assertUnreachable()

```ts
function assertUnreachable(unexpectedValue): never;
```

Defined in: [packages/bus-core/src/util/assert-unreachable.ts:4](https://github.com/node-ts/bus/blob/2e6cf65c27833b707ae31ee623cfb6343770f434/packages/bus-core/src/util/assert-unreachable.ts#L4)

This raises transpile time errors any time the tokenizer hits this function in the code

## Parameters

| Parameter | Type |
| ------ | ------ |
| `unexpectedValue` | `never` |

## Returns

`never`