> ## Documentation Index
> Fetch the complete documentation index at: https://dev.smile.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Error handling

The SDK uses a consistent error-handling approach to make it easy to detect, differentiate, and respond to different types of issues. Errors are categorized into three types:

1. **Warnings:** Non-critical issues that do not interrupt normal execution. These are logged to the console using `console.warn()` or `console.error()`, depending on severity.
2. **Unexpected Errors:** Indicate incorrect or unsupported use of the SDK. These are thrown as standard JavaScript `Error` instances with descriptive messages to help identify the problem.
3. **API Errors:** Occur when a request to Smile's API fails. These are thrown as `ApiError` instances, which extend the native `Error` class and include additional details about the HTTP response and API context (see [ApiError object](/js/concepts/error-object)).

## Determining the type of error

The best way to differentiate between the two types of error objects that may be thrown depends on your build environment:

* In a **typed** environment, use `ApiError.isApiError()`.
* In a **non-typed** environment, check for the presence of a `status` property on the error object. If it's present and has a numeric value, then it's an API error.

## Error handling example

<CodeGroup>
  ```javascript JavaScript lines theme={null}
  // In plain JavaScript
  try { ... } catch (error) {
    if (error && typeof error === 'object' && typeof error.status === 'number') {
      // Handle API error
    } else {
      // Handle unexpected error
    }
  }
  ```

  ```typescript TypeScript lines theme={null}
  // In compiled TypeScript
  import { ApiError } from '@smile-io/smile-js';

  try { ... } catch (error) {
    if (ApiError.isApiError(error)) {
      // Handle API error
    } else {
      // Handle unexpected error
    }
  }
  ```
</CodeGroup>