The SharePoint Framework (#SPFx) Extensions Dev Preview Drop 1 utilizes a new version of one of the core node modules, sp-webpart-base v1.1.1. This module removed, possibly by accident, a particular TypeScript definition file, Placeholder.d.ts found in \node_modules\@microsoft\sp-webpart-base\lib\components\placeHolder. Unfortunately this change was not included in the release notes, so it went unnoticed for a few days until rgueldenpfennig […]