SIERRA Leone's ex-president Ernest Bai Koroma left the West African country by plane and flew to Nigeria, two Reuters reporters said, after a court allowed him to travel abroad on medical grounds despite treason charges. On January 3, 70-year-old Koroma was charged with four offences for his alleged role in a failed military attempt to topple the government in November, but a high court on Wednesday ruled he could leave the country. The decision came amid concerns his indictment could stoke domestic tensions linked to the 2023 election, which saw President Julius Maada Bio reelected for a second term although the main opposition candidate rejected…