Fix error when there is no Rails config

lib/brakeman/checks/base_check.rb

@@ -148,6 +148,7 @@ class Brakeman::BaseCheck < Brakeman::SexpProcessor
     @mass_assign_disabled = false
 
     if version_between?("3.1.0", "4.0.0") and 
+      tracker.config[:rails] and
       tracker.config[:rails][:active_record] and 
       tracker.config[:rails][:active_record][:whitelist_attributes] == Sexp.new(:true)
 

lib/brakeman/checks/check_forgery_setting.rb

@@ -11,7 +11,8 @@ class Brakeman::CheckForgerySetting < Brakeman::BaseCheck
 
   def run_check
     app_controller = tracker.controllers[:ApplicationController]
-    if tracker.config[:rails][:action_controller] and
+    if tracker.config[:rails] and
+      tracker.config[:rails][:action_controller] and
       tracker.config[:rails][:action_controller][:allow_forgery_protection] == Sexp.new(:false)
 
       warn :controller => :ApplicationController,