Homography::then_after returned products whose entries could overflow to
infinity or become NaN. A move, transform or grid reproject of type or a
symbol instance whose stored projection has large finite entries stored such
a product, and the type was then drawn flat, since a projection that is not
finite reads as none.
- Homography::checked_then_after returns None when an entry of the product
is not finite.
- project_node composes each type and symbol instance projection with it and
returns false, leaving the object as it is, when one would not be finite;
moves and transforms in perspective and Define Perspective Grid with
reproject then return the horizon error and leave the document unchanged.
- transform_map, attach_homography and size_homography return None for such
a product.
- Edit Text returns the horizon error, and does not enter isolation mode,
when the type cannot be shown flat where it is drawn.