[3.13] gh-121860: Fix crash when materializing managed dict (GH-121866) (#121867)

The object's inline values may be marked invalid if the materialized
dict was already initialized and then deleted.
(cherry picked from commit 162b41f57757c1df40eb377985e2e877fb0f0ea3)

Co-authored-by: Sam Gross <colesbury@gmail.com>