In the legacy architecture, List Widget meta first item was rendering in
edit mode allowing DnD, resize, etc while the rest of the items were
rendering in view mode restricting any editing experience.
The first item was being used as a template to decide what the template
was going to be for rest of the items.
However after the overhaul of BaseWidget and CanvasWidget render mode is
always EDIT or VIEW for all widgets so DropTarget had to render a meta
canvas widget which it was not written to handle. so have added checks
to make sure DropTarget does not render and wrap widgets that do not
have a parent.
Ideally this should have been caught in the CI, there are tests already
but the checks were happening to check if List widget was allowed inside
another List widget but the other items that were rendering in view mode
were not being asserted.
I have added tests to check if all nested widgets are properly rendered
and there is no "Oops, something went wrong" error. This should make
sure this issue does not get past CI in the future.
(cherry picked from commit 6355e7a697)
15f7580d87