Move map default options to initialization hook

app/model_factories/carto/visualization_factory.rb

@@ -30,13 +30,11 @@ module Carto
       layers = [base_layer, data_layer]
       layers << Carto::LayerFactory.build_default_labels_layer(base_layer) if base_layer.supports_labels_layer?
 
-      options = Carto::Map::DEFAULT_OPTIONS.merge(
+      Carto::Map.new(
         user: user,
         provider: Carto::Map.provider_for_baselayer_kind(base_layer.kind),
         layers: layers
       )
-
-      Carto::Map.new(options)
     end
     private_class_method :build_canonical_map
   end

app/models/carto/map.rb

@@ -74,7 +74,7 @@ class Carto::Map < ActiveRecord::Base
     bounding_box_sw: [BoundingBoxHelper::DEFAULT_BOUNDS[:minlat], BoundingBoxHelper::DEFAULT_BOUNDS[:minlon]].to_s,
     bounding_box_ne: [BoundingBoxHelper::DEFAULT_BOUNDS[:maxlat], BoundingBoxHelper::DEFAULT_BOUNDS[:maxlon]].to_s,
     provider:        'leaflet',
-    center:          [30, 0]
+    center:          [30, 0].to_s
   }.freeze
 
   serialize :options, ::Carto::CartoJsonSerializer
@@ -229,6 +229,12 @@ class Carto::Map < ActiveRecord::Base
   end
 
   def ensure_options
+    self.zoom ||= DEFAULT_OPTIONS[:zoom]
+    self.bounding_box_sw ||= DEFAULT_OPTIONS[:bounding_box_sw]
+    self.bounding_box_ne ||= DEFAULT_OPTIONS[:bounding_box_ne]
+    self.center ||= DEFAULT_OPTIONS[:center]
+    self.provider ||= DEFAULT_OPTIONS[:provider]
+
     self.options ||= {}
     options[:dashboard_menu] = true if options[:dashboard_menu].nil?
     options[:layer_selector] = false if options[:layer_selector].nil?