Fix base error class for v2.

Author: Jeff Dutil

lib/aws/session_store/dynamo_db/locking/base.rb

@@ -56,7 +56,7 @@ def delete_session(env, sid)
     def handle_error(env = nil, &block)
       begin
         yield
-      rescue Aws::DynamoDB::Errors::Base => e
+      rescue Aws::DynamoDB::Errors::ServiceError => e
         @config.error_handler.handle_error(e, env)
       end
     end