Premiere Beta 26.0.0 build 27: AdobeXMPScript error, alert is not a function

In Premiere Beta 26.0.0 build 27 (macOS), I found 2 bugs:

1) Can't use lib:AdobeXMPScript as ExternalObject

new ExternalObject("lib:AdobeXMPScript") // IOError: I/O error

2) Can't use alert function

alert("Hello") // alert is not a function

This breaks half of my extensions. I rely on AdobeXMPScript to add metadata to project items.