No, those get set in the call to `queryPreviewProviders()` a couple lines up (or from popover param passed in from unit test).

When mouse is "hovering over dead space", `popoverState` is created so we can save timer reference in `popoverState.hoverTimer`. If mouse doesn't move for 350ms, then `showPreview()` gets called, `queryPreviewProviders()` returns `null`,  `popoverState.start` is undefined, and code does nothing.