When making an Item model, initialize description to an empty string.
When making an Item model, initialize description to an empty string.

Previously, some item descriptions were being set to None. Now peewee
thinks that because it has a value, it doesn't set it to our default
value anymore (""). Now instead we add a step where if item.description
is falsey then we initialize it to an empty string. Now SQLite doesn't
complain anymore.

fle-internal/content-pack-maker