I've noticed that in a lot of examples of "ergative languages," there is some piece of the language that does not fit the pattern we call "ergativity." For example, Basque does not mark ergative case in the progressive aspect, and Dyirbal pronouns have a nominative-accusative looking pattern.
Are there examples of a language where every aspect (no pun intended) of the language fits the mold of "ergativity?" Is it reasonable to expect to find one (do we expect a nominative-accusative language to be totally nominative-accusative)?