Remove extra comma from JSON repr (#184)

Author: martinRenou

python/jupytergis_core/src/jgisplugin/plugins.ts

@@ -122,7 +122,7 @@ const activate = (
         format: 'text',
         size: undefined,
         content:
-          '{\n\t"layers": {},\n\t"sources": {},\n\t"options": {"latitude": 0, "longitude": 0, "zoom": 0, "bearing": 0, "pitch": 0, "projection": "EPSG:3857"},\n\t"layerTree": [],\n}'
+          '{\n\t"layers": {},\n\t"sources": {},\n\t"options": {"latitude": 0, "longitude": 0, "zoom": 0, "bearing": 0, "pitch": 0, "projection": "EPSG:3857"},\n\t"layerTree": []\n}'
       });
 
       // Open the newly created file with the 'Editor'