# Errors

Skema uses [err-object](https://github.com/kaelzhang/node-err-object) to standardize error objects.

There are two kinds of errors
- data errors
- initialization errors

## Initialization Errors

Initialization errors are generated by methods other than `.from()`, such as `shape()`, `type()`, etc. And they have following properties:

- **code** `string(UPPERCASED_STRING)` error codes.
- **message** `string` The error message.
- **args** `Array<any>` The arguments passed to message template of the error.

```js
Error {
  message: "unknown type 'hahaha'",
  args: ['hahaha'],
  code: 'UNKNOWN_TYPE'
}
```

## Data Errors

Data errors are generated by `.from()` method, and have following properties:

- **input** `any` The input value of the current property
- **key** `string | number | null` the key of the current property
  - `string` if the parent is an object
  - `number` if the parent is an array
  - `null` if there is no parent
- **path** The accessing path of keys to reach the current property
- **code**
- **message**
- **args**

[Examples🔬](https://jsfiddle.net/kaelzhang/scvLn8Ly/)