See BWO19 v Minister for Immigration, Citizenship, Migrant Services and Multicultural Affairs [2020] FCAFC 181 at [119]ff where the Court dissects a credibility finding, and concluded that the Tribunal would have used the same credibility reasoning even if it had not asked improper questions requiring waiver of privilege, and denied the applicant the procedural fairness he should have been given–and even when those errors went directly to the credibility reasoning that was actually adopted.