When trying to use applets in 0.18.1 via a globally installed toolkit, you will get the following error:

Error: The child XXX of Program must be a Stack

This is because when the toolkit is globally installed, the copy of @aws-cdk/cdk (which defines Stack) is different than the one installed in the local node_modules. In JavaScript, instanceof is based on constructor object equality and they have to be the exact same copy in order to align.

Reported by @clareliguori