Fix sentry errors in old carto module

app/controllers/users/carte_controller.rb

@@ -65,9 +65,13 @@ class Users::CarteController < UsersController
     # https://tools.ietf.org/html/rfc7946#section-3.1.6
     if json_latlngs.present?
       multipolygone = JSON.parse(json_latlngs)
-      multipolygone.reject! { |polygone| polygone.count < 4 }
-      if multipolygone.present?
-        multipolygone.to_json
+      if multipolygone.first == ["error", "TooManyPolygons"]
+        [].to_json
+      else
+        multipolygone.reject! { |polygone| polygone.count < 4 }
+        if multipolygone.present?
+          multipolygone.to_json
+        end
       end
     end
   end

app/helpers/application_helper.rb

@@ -91,7 +91,7 @@ module ApplicationHelper
   end
 
   def ensure_safe_json(json)
-    JSON.parse(json).to_json
+    json.present? ? JSON.parse(json).to_json : '[]'
   rescue Exception => e
     Raven.capture_exception(e)
     {}