Dashboard aggregation issue showing exception errors

The customer was trying to build an aggregation using a field called 'version' from a specific stream (which is tied to a specific index). As the error message says, this field does exist in logs from another stream, which is mapped to a different index.

## Expected Behavior

Prevented aggregating field e.g. the sidebar or inline from a message, but not inside the aggregation builder itself. we need to take care of that.

## Current Behavior

Building aggregation returns an exception error.

## Possible Solution

## Steps to Reproduce (for bugs)

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## Context

Here is support ticket: https://support.graylog.com/#ticket/zoom/3663

## Your Environment

* Graylog Version:
* Elasticsearch Version:
* MongoDB Version:
* Operating System:
* Browser version: