Kibana version: 6.2.2

Elasticsearch version: 6.2.2

Server OS version: RHEL 7

Browser version: Google Chome Version 66.0.3359.139 (Official Build) (64-bit)

Browser OS version: Windows 10 1609

Original install method (e.g. download page, yum, from source, etc.): yum

Description of the problem including expected versus actual behavior:
Using Kibana, when exporting a CSV from an index pattern which includes closed indices, Kibana reports the exception 'index_closed_exception', and fails.
It should ignore the closed indices, and use the open ones.

Steps to reproduce:

1. Create two identical indices
2. Put some events on them
3. Create an index pattern in Kibana which includes both indices
4. Close only one of them.
5. Export a CSV, which will fail.

Errors in browser console (if relevant): Not relevant

Provide logs and/or server output (if relevant): index_closed_exception

Discussion thread with more details: https://discuss.elastic.co/t/export-to-csv-fails-with-index-closed-exception/130840