The "Copy page hierarchy" API throws a NullPointerException when the source page has an emoji or a header image in its title

Issue Summary

The "Copy page hierarchy" API throws a NullPointerException when the source page has an emoji or a header image in its title.

Steps to Reproduce

1. Create a page with either an emoji or a header image in its title
2. Copy the page using the "copy page hierarchy"

Expected Results

The page hierarchy is successfully copied.

Actual Results

The page hierarchy fails and the response contains a NullPointerException:

"errors":[ 
 { "key":"NullPointerException",
   "type":"ERROR",
   "args":[],
   "translation":null }]

Workaround

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