part of strict null work

es6 aftermath, static property of type X are created before decorating type X and therefore failing the instanceof-check

In conjunction with setting `editor.multiCursorModifier` to `ctrlCmd`, this yields a much more natural `alt+click` experience. The goofier `shift+alt+click` that is the default uses the _prior_ cursor position as the start point of the column selection.

Fixes #68425

Fixes #68335

Strict null work

Supress access to arrays that we know are set earlier in the code