Do not throw error out of the box if no user class is defined

app/models/blazer/query.rb

@@ -1,7 +1,5 @@
 module Blazer
   class Query < ActiveRecord::Base
-    belongs_to :creator, class_name: Blazer.user_class.to_s if Blazer.user_class
-
     validates :name, presence: true
     validates :statement, presence: true
 

lib/blazer.rb

@@ -14,7 +14,6 @@ module Blazer
   self.audit = true
   self.user_name = :name
   self.timeout = 15
-  self.user_class = "User"
 
   def self.time_zone=(time_zone)
     @time_zone = time_zone.is_a?(ActiveSupport::TimeZone) ? time_zone : ActiveSupport::TimeZone[time_zone.to_s]

lib/blazer/engine.rb

@@ -7,6 +7,8 @@ module Blazer
       app.config.assets.precompile << proc { |path| path =~ /\Ablazer\/application\.(js|css)\z/ }
 
       Blazer.time_zone ||= Time.zone
+      Blazer.user_class ||= User rescue nil
+      Blazer::Query.belongs_to :creator, class_name: Blazer.user_class.to_s if Blazer.user_class
     end
   end
 end