The search does not work because it tries to load an HTTP URL from an HTTPS page:
Blocage du chargement du contenu mixte actif (mixed active content) « http://nominatim.openstreetmap.org/search?format=json&q=diderot&json_callback=L.Control.Search.callJsonp »
The search does not work because it tries to load an HTTP URL from an HTTPS page: