The first error seems to be unrelated to the client library, it seems as if DAP API would be returning records in the output that are not compliant with the declared table schema.
The second error is also a schema compatibility issue. In earlier versions of DAP API, the enumeration web_conferences__conference_type had a duplicate value but with a different character case: DimDim and dimdim. This has already been addressed in DAP API long ago (and the all lowercase version was removed) but if you have a database table schema from that time, the DAP API schema and the local database schema are now different. The straightforward solution is to drop the table (dropdb), and fetch a new snapshot (initdb), which will continue to work with successive incremental updates (syncdb). The more complex solution is to re-cast the column in the expected SQL type such that it becomes
CREATE TYPE "canvas"."web_conferences__conference_type" AS ENUM ('__dap_unspecified__', 'AdobeConnect', 'BigBlueButton', 'CiscoWebex', 'DimDim', 'Wimba', 'Wiziq');
I recommend reporting these errors to Instructure support such that they can be properly tracked.