Standardize CRUD errors returned

With Create call to a public read, RLS active database, the return object is error-coded as a row level security violation:
Object {code: "42501", details: null, hint: null, message: 'new row violates row-level security policy for table "xxxx"'}

The Update call to the same database fails silently, returns an empty data array and null error. This empty data array causes real pain. It should not fail silently, but return an object with an error code similar to Create.

All CRUD calls should return error codes. These should be consistent, and match the documentation.