When the object we iterate over is not part of the depsgraph, we cannot
get the evaluated copy to export. This workaround is temporary to avoid
a BLI_assert() failure getting the evaluated mesh of this object.
This will be handled more elegantly in the new AbstractHierarchyIterator
that I'm working on, but that requires a bigger change than we should
allow this close to the 2.80 release candidate.
This fixes a problem described in T58686.
0829bd7b66