[EPM] Error trying to view index pattern when no matching indices exist

[neptunian]

We create the index pattern when a user installs a package. In the Kibana Management UI, if the user tries to view an index pattern it will fail (see screenshot). When loading an index pattern for the first time the UI checks for some field properties on each field and adds the readFromDocValues property to each field (along with others, I believe, like esTypes) and saves the index pattern. In order to do this it needs to fetch the fields but since no matching indices exists it will fail. This issue already exists (see links below) in other scenarios such as with metricbeat when the user runs setup before starting to collect data but is probably unlikely to do that. In the context of the Ingest Manager we think it's more likely they will run into this. Solution for now is to document and make the user aware of the issue. Another partial solution could be improving the error message the user is presented with so they understand they need to have an index first.

Similar Issues and background:
#35898
#35481
#40071

[elasticmachine]

Pinging @elastic/ingest (Feature:EPM)

[elasticmachine]

Pinging @elastic/kibana-app-arch (Team:AppArch)

[streamich]

To reproduce the error start Kibana with

yarn start --xpack.ingestManager.enabled=true --xpack.ingestManager.epm.enabled=true

And then you need to execute POST request once to the server

    core.http
      .post('http://localhost:5603/<YOUR_PREFIX>/api/ingest_manager/epm/packages/system-0.9.0')
      .then(console.log, console.log);