If you send a request to the REST API with invalid JSON in body than it will now return a error. This assists developers if they accidentally send invalid JSON and wonder why their data appears to be ignored. Props rmccue. Fixes #38547. Built from https://develop.svn.wordpress.org/trunk@39109 git-svn-id: http://core.svn.wordpress.org/trunk@39051 1a063a9b-81f0-0310-95a4-ce76da25c4cd