Do not create nullptr SkTypeface_proxy

Bug: 404625324
Change-Id: I30b4a8963a471d0b469675ae5e0be077c5fa0cd5
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/966976
Reviewed-by: Julia Lavrova <jlavrova@google.com>
Commit-Queue: Ben Wagner <bungeman@google.com>
5 files changed