- All [operational errors][joyent-guide] are rejected with a [FetchError](https://github.com/bitinn/node-fetch/blob/master/README.md#class-fetcherror). You can handle them all through the promise `catch` clause.
- All errors originating from Node.js core are marked with `err.type = 'system'`, and in addition contain an `err.code` and an `err.errno` for error handling. These are aliases for error codes thrown by Node.js core.
- [Programmer errors][joyent-guide] are either thrown as soon as possible, or rejected with default `Error` with `err.message` for ease of troubleshooting.
- Because we maintain 100% coverage, see [test.js](https://github.com/bitinn/node-fetch/blob/master/test/test.js) for a full list of custom `FetchError` types, as well as some of the common errors from Node.js