Empty indices are incorrectly included in the search target

Empty indices are INCORRECTLY included in the search target

Expected Behavior

Only indices with messages should be targeted

Current Behavior

Empty indices are INCORRECTLY targeted in EVERY search

Steps to Reproduce (for bugs)

1. Make sure that you have at least one empty index which is NOT active write index
2. Make a search using what ever settings you like
3. Empty index is included in the search target

Context

Confuses user when it seems that a simple queries might seem to target multiple indices

Your Environment

• Graylog Version: 3.0.1
• Elasticsearch Version: 6.7.2
• MongoDB Version: 4.0.7
• Operating System: CentOS 7
• Browser version: Safari