Social Activities portlet error when viewing RSS feed

• Type: Bug
• Status: Closed
• Resolution: Fixed
• Affects Version/s: 7.0.0 M5
• Fix Version/s: 7.0.0 M5
• Component/s: Social Activity, Social Networking
• Labels: None
• Story Points: 6
• Fix Priority: 4
• Git Pull Request: https://github.com/brianchandotcom/liferay-portal/pull/25446

Steps to reproduce:

1. Go to any public page and add the "Activities" portlet to the page.
2. Click on the "Subscribe to Liferay's activities" link

Expected: a new window/tab is opened with an RSS feed
Actual: an error is shown in the logs and the RSS feed fails to load