Babel build error when running coverage test with ember-cli-code-coverage

On any version of ember-cli-code-coverage over 1.0.0-beta.4 I get the same error

Build failed.
Build Error (Babel) in chat/components/chat-box.js

chat/components/chat-box.js: You gave us a visitor for the node type "ClassPrivateProperty" but it's not a valid type

chat-box.js has nothing to do with the error so it makes no sense and it also has no test for it.

So why am I getting this error and what does it mean?