Destroy farmOS-map instances when Drupal behaviors are detached.

modules/farm/farm_map/js/farm_map.js

@@ -13,6 +13,11 @@
           farmOS.map.create($(element).attr('id'), options);
         });
       });
+    },
+    detach: function (context, settings) {
+      $('.farm-map', context).each(function (index, element) {
+        farmOS.map.destroy($(element).attr('id'));
+      });
     }
   };
 }(jQuery));