Kibana: Deleted index pattern still shows up in discover under index patterns and navigation to discover has a problem

[bhavyarm]

Kibana version: 7.7.0 BC5

Elasticsearch version: 7.7.0 BC5

Server OS version: darwin_x86_64

Browser version: chrome latest

Browser OS version: OS X

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

Describe the bug: If user deletes an index pattern two things happen:

1. If its default index pattern - clicking on discover just hangs the UI.
   user cannot navigate to discover unless otherwise she clicks on management. But the deleted default index pattern still shows up in discover side nav under index patterns
2. If its non-default index pattern - user can navigate to discover but the deleted index pattern still shows up in discover

Steps to reproduce:

Default

1. Go to index patterns under management - delete the default index pattern - click on discover
2. Clicking on discover just hangs the UI on an empty screen
3. Click on management in the header and then discover - user can finally navigate to discover
   (This seems to be a special case only with sample data if its user created index pattern then navigation goes through fine)
4. But deleted default index pattern still shows up in discover under index patterns

Non-default:

1. Go to index patterns under management - delete the non default index pattern - click on discover
2. User can navigate to discover
3. But deleted default index pattern still shows up in discover under index patterns

[elasticmachine]

Pinging @elastic/kibana-app (Team:KibanaApp)

[bhavyarm]

Same in 7.6.2 not a regression!

[kertal]

Similar problem here:

62269

Will provide a solution, thx for reporting!