Related #3582

@refset mind fleshing this out with why (if indeed we know)?

PostgresJS fetches the oids of array types at the first connection, in order to install type parsers/serializers for those array types. We don't currently have array types in our pg_catalog.pg_type table, so this wouldn't actually do anything. We also don't support some of the columns in the query (see #3582). So in practice we could just document the use of fetch_types: false.

However, I think it's important to clarify why that initial query fails with a 'malformed-query' error. The query should actually work I think and return no rows.