Loading some Advanced Roadmaps for Jira (AR4J) pages fails with "Unknown page type" error in the browser console log

Issue Summary

When a page decorator is added to the HTML, then some Advanced Roadmaps for Jira (AR4J) pages fails to load.

For example, loading the View Plans page shows doesn't load as the image below.

The page decorator can be loaded as a custom code in the Announcement Banner or can be used by a Marketplace App.

Steps to Reproduce

1. Install a vanilla instance of Jira Software DC.
2. Access Plans > View Plans and notice the page loads properly.
3. Edit the announcement banner to have the following tag; this is the fastest way to reproduce the issue.

   <meta name="decorator" content="atl.general" />
   

4. Access Plans > View Plans and notice the page won't load.

Expected Results

The page loads properly without an error.

Actual Results

The page won't load and we have the following error in the browser console log.

Uncaught Error: Unknown page type <decorator name>

Workaround

Currently there is no known workaround for this behavior. A workaround will be added here when available.