Using the github head I got this
Uncaught TypeError: this.view.state.selection.eq is not a function
at SelectionReader.readFromDOM (bundle_pm.js:12550)
at HTMLDocument.SelectionChangePoller.readFunc (bundle_pm.js:12569)
If I inspect this.view.state.selection
in the debugger, it is indeed a Selection object but does not have an eq method