I fixed it. Just added default values of "0" to the offending columns.
use ipb_database;
ALTER TABLE ipbforums_topics ALTER cache_sm SET DEFAULT 0;
ALTER TABLE ipbforums_topics ALTER cache_date SET DEFAULT 0;
describe ipbforums_topics;
... but maybe there are others in the database that need correcting. Can someone from Invision let me know? I'm sure you want to know about this bug I encountered too.
Normally I'd post something in the client area but it looks like you've removed my ability.
CA3LE's post in IPS\Db\Exception: Field 'cache_sm' doesn't have a default value (1364) was marked as the answer