PARIS – Wearing hard hats and protective suits, the choir of Notre Dame Cathedral sang inside the medieval Paris landmark for the first time since last year’s devastating fire for a special Christmas Eve concert.Accompanied by an acclaimed violinist, a rented organ and a soprano soloist, 20 singers performed beneath the cathedral’s stained-glass windows amid the darkened church, which is transitioning from being a precarious hazardous clean-up operation to becoming a massive reconstruction site.The singers stood socially distanced to be able to take off their masks — which is required indoors in France to stem the spread of the virus — and sing.The concert was recorded Saturday and will be broadcast Thursday night.