Not all database interactions ensure rollback if transaction fails

At present, in the rdbmsstore module, not all database interactions are included in try/catch blocks. The consequence of this is that

if the database connection fails, then transaction rollback may not occur
subsequent database interactions, if the connection is restored, may be rejected due to an incompletely rolled back transaction. These manifest themselves as a PendingRollbackError on reconnection https://sentry.io/organizations/university-of-oxford-gpas/issues/2777519950/?project=5954139&query=is%3Aunresolved

davidhwyllie / findNeighbour4