[ts] Experimental support for decorators is a feature that is subject to change in a future release. Set the 'experimentalDecorators' option to remove this warning. [1219]

This means setting javascript.implicitProjectConfig.experimentalDecorators to true at C:\Users\Thomas\AppData\Roaming\Code\User\settings.json or where else you may have this file at. At: File > Preferences > Settings ...click the three dots in a horizontal line at the upper left of Visual Studio Code 1.29.1 and pick "Open settings.json" to get at this.