By Kirstin Ridley LONDON (Reuters) – The head of the UK Serious Fraud Office (SFO) was on Tuesday accused of “very, very basic errors in litigation” and hiding behind a review into the agency’s failings in a tetchy grilling by lawmakers. Lisa Osofsky said she was duty bound to wait for the recommendations of former High Court judge David Calvert-Smith before being drawn on how two convictions in the high-profile Unaoil bribery prosecution were quashed by the Court of Appeal. Calvert-Smith was appointed by the Attorney General in February to launch a forensic review into SFO failings – and Osof…