mejor soporte de errores

app/jobs/backtrace_job.rb

@@ -4,6 +4,8 @@
 class BacktraceJob < ApplicationJob
   class BacktraceException < RuntimeError; end
 
+  EMPTY_SOURCEMAP = { 'mappings' => '' }.freeze
+
   queue_as :low_priority
 
   attr_reader :params, :site_id
@@ -67,14 +69,18 @@ class BacktraceJob < ApplicationJob
   # @param [String] La URL del map
   # @return [Hash]
   def data(map)
-    return {} unless map.start_with? 'https://'
+    return EMPTY_SOURCEMAP unless map.start_with? 'https://'
 
     map += '.map' unless map.end_with? '.map'
 
     @data      ||= {}
+    # TODO: Soportar ETags para la descarga, probablemente pasar a
+    # Faraday con caché para esto.
     @data[map] ||= FastJsonparser.parse(Rails.cache.fetch(map, expires_in: 12.hours) do
                                           Down.open(map).read
                                         end, symbolize_keys: false)
+  rescue Down::Error, FastJsonparser::Error
+    EMPTY_SOURCEMAP
   end
 
   # Asume que todos los sourcemaps comparten la misma URL, lo
@@ -85,13 +91,8 @@ class BacktraceJob < ApplicationJob
   #
   # @return [SourceMap::Map]
   def sourcemap
-    @sourcemap ||=
-      begin
-        sources.map do |map|
-          SourceMap::Map.from_hash data(map)
-        rescue Down::Error, FastJsonparser::Error
-          SourceMap::Map.new
-        end.reduce(&:+)
-      end
+    @sourcemap ||= sources.map do |map|
+      SourceMap::Map.from_hash data(map)
+    end.reduce(&:+)
   end
 end