Issue Summary

When "_" is used as heading 6 and is aligned to the right, page sometimes fails to load

Steps to Reproduce

1. Create a page and enter "_"
2. Set the format as heading 6 and align it to right
3. Publish the page
4. Reload several times

Expected Results

The page will be loaded

Actual Results

For most of the times, after the page loads for a second, an error will be shown.

Error's description:

Something went wrong
Our team has been notified. If the problem persists, please contact Atlassian Support and be sure to give them this code: 6r3bm4.


Reload this page

Notes

• This can also happens with other heading levels, such as h2
• Also happens without aligning the text to right

Workaround

Avoid using the combination of "_", heading 6, align to right.