Summary
This module is an extension to the REST module.
In case user wants error codes to be added in response then just enable this module.

e.g.
with this the webservice response will be,
{
"FailureReason": {
"message": "Field values for \"name\" must use an array structure",
"error_code": 422
}
}

instead of
{
"message": "Field values for \"name\" must use an array structure"
}