TypeError: null is not a function occurs when selecting a wiki document in site administration

• Type: Regression Bug
• Status: Closed
• Resolution: Fixed
• Affects Version/s: Master
• Fix Version/s: 7.0.0 DXP FP6, 7.0.0 DXP SP1, 7.0.0 DXP SP2, 7.0.3 CE GA4, 7.1.X, Master
• Component/s: Collaboration, Collaboration > Wiki
• Labels:
  • front-end
  • liferay-digital-enterprise-70-sp1
  • liferay-fixpack-de-6-7010
• Branch Version/s:
  7.0.x
• Backported to Branch:
  Committed
• Fix Priority: 4
• Last Working Version:
  Master
• Sprint: Manganbabingtonite, Sphaerosiderite 12/6-12/20
• Git Pull Request: https://github.com/brianchandotcom/liferay-portal/pull/43225

Steps to reproduce:

1. Go to Content > Wiki
2. Add a new wiki page
3. Navigate to wiki page in descriptive view
4. Open browser console
5. Select the wiki page by clicking the checkbox

Expected results:
No JS error appears in the console.

Actual results:
TypeError: null is not a function appears in the console.

Reproduced on:
Tomcat 8.0.32 + MySQL 5.6.
Portal master GIT ID: 71c79f972d2817e3662facfdfcafbb27a7528d3b