Check for nil

Author: pacso

lib/ice_cube/schedule.rb

@@ -433,7 +433,7 @@ def enumerate_occurrences(opening_time, closing_time = nil, options = {})
         t1 = start_time if t1 < start_time
         loop do
           break unless (t0 = next_time(t1, closing_time))
-          break if t0 < options[:range_start]
+          break if options.has_key?(:range_start) && t0 < options[:range_start]
           break if closing_time && t0 > closing_time
           if spans ? (t0.end_time > opening_time) : (t0 >= opening_time)
             yielder << (block_given? ? yield(t0) : t0)