Update schemas declare fields `X | None = None` so a PATCH can leave
them out, and most routes treat null as "unchanged". About a dozen
(printers, smart plugs, queue items and bulk edits, archives,
filaments, spools, notification providers, GitHub backup, HA sensors,
maintenance, external links) applied model_dump(exclude_unset=True)
with setattr instead, wrote the null into a NOT NULL column and failed
with a 500.
A new base, IgnoresNullForRequiredColumns, drops such a null before
validation, using the NOT NULL flags of the table the schema names
(__orm_table__, resolved lazily), so every route treats it as not sent.
A null for a nullable column still clears it. 40 update schemas use it;
a guard test requires every PATCH/PUT body that writes a row to use it
or to be listed with a reason (suppliers keep their own 422 for a null
name).
maziggy