Enabling then deleting a page on a site page variation causes all of staging to crash

• Type: Bug
• Status: Closed
• Resolution: Fixed
• Affects Version/s: 6.1.30 EE GA3
• Fix Version/s: 6.1.2 CE GA3, 6.1.30 EE GA3, 6.1.X EE, 6.2.0 CE B1
• Component/s: Content Publishing > Staging
• Labels:
  • 6.1_release_notes
  • QA-AUTOMATION
  • QA-KC
  • QA-R
  • pc_30
• Environment: Tomcat 7 + MySQL 5. Portal 6.1.x GIT ID: 487767f5fdd6e62db33580ca8cb233dd427fa2af.
• Branch Version/s:
  6.1.x
• Backported to Branch:
  Committed
• Epic/Theme:
  • LPS-37514
• Fix Priority: 5
• Sprint: Sprint 1
• Git Pull Request: https://github.com/brianchandotcom/liferay-portal/pull/12452
• Bug Type: Regression Bug

1. Create a Blank Site.
2. Go to Site Pages and Add a Page (Page1) to the Blank Site.
3. Go to Site Settings and under Advanced, select Staging.
4. Flag "Local Live" and "Enabled On Public Pages".
5. Navigate to the Blank Site.
6. Enter Staging Mode.
7. In the Staging dropdown menu, select "Manage Site Pages Variations".
8. Add a Site Page Variation (VariationA) and copy pages from the Main Variation.
9. Navigate to the newly-created variation.
10. Add a page (PageA) then go to PageA.
11. Mark that page as "Ready for Publication".
12. Switch over to the Main Variation.
13. Enable PageA on the Main Variation.
14. At this moment, there is an error where the page will not actaully enable. (LPS-36567) A workaround for this is to undo and then redo the action in the bar at the top of the page.
15. Delete the enabled page by navigating to Page1 and then hovering over the PageA tab and clicking the x.
16. Click on (VariationA).
17. Going to the Staging Site will throw a console error and the UI is unavailable.

Expected result:
VariationA page will show.

Actual result:
VariationA page does not show and instead, the page shows:

an-unexpected-system-error-occurred 

java.lang.IllegalStateException: java.lang.NullPointerException"

Now staging will not work for that site permanently and will instead show the above message each time staging is selected.