Error on empty result from table definition queries

See the comments. Basically any query generator that relies on information_schema will just return an empty result if the table and/or schema are spelled incorrectly, or with the wrong case. Sequelize would just error out with a confusing error further up the stack when a function like `renameColumn` attempted to enumerate an empty table definition.

It would be nice to backport this to 1.7 also.