UpdateByQuery issue

[rtwent]

Given:
ES: 7.17
ruflin/elastica: 7.2.0 (but the issue is present on the dev version too)

Background: Due to architectural issues - we run updateByQuery in loop. Troubles in debugging had appeared.

By the ES documentation the response of UpdateByQuery request is documented. It seems, for now, is impossible to retrieve the message, why request was failed.

Response::HasError() will always return false, because of error property is not documented for _update_by_query. As a result error message will be empty:

Elastica/src/Response.php

Lines 134 to 139 in e2cb89b

	public function hasError()
	{
	$response = $this->getData();
	return isset($response['error']);
	}

isOk is a way to identify the response status. But still, no error message will be provided.

Example of failed response from elastic:

{
  "took":2,
  "timed_out":false,
  "total":1,
  "updated":0,
  "deleted":0,
  "batches":1,
  "version_conflicts":1,
  "noops":0,
  "retries":{
    "bulk":0,
    "search":0
  },
  "throttled_millis":0,
  "requests_per_second":-1,
  "throttled_until_millis":0,
  "failures":[
    {
      "index":"xxxxx",
      "type":"_doc",
      "id":"xxxxxx",
      "cause":{
        "type":"version_conflict_engine_exception",
        "reason":"[xxxxxx]: version conflict, required seqNo [15668298], primary term [2]. current document has seqNo [15668306] and primary term [2]",
        "index_uuid":"wUFh0yvBRkavh7cCHAxWcg",
        "shard":"1",
        "index":"xxxxx"
      },
      "status":409
    }
  ]
}