Make segment operators nil-safe

Avoid `NoMethodError` when evaluating nil trait values

Author: rolodato

lib/flagsmith/engine/segments/models.rb

@@ -42,10 +42,10 @@ class Condition
           LESS_THAN => ->(other_value, self_value) { other_value < self_value },
           LESS_THAN_INCLUSIVE => ->(other_value, self_value) { other_value <= self_value },
           NOT_EQUAL => ->(other_value, self_value) { other_value != self_value },
-          CONTAINS => ->(other_value, self_value) { other_value.include? self_value },
+          CONTAINS => ->(other_value, self_value) { other_value&.include? self_value },
 
-          NOT_CONTAINS => ->(other_value, self_value) { !other_value.include? self_value },
-          REGEX => ->(other_value, self_value) { other_value.match? self_value }
+          NOT_CONTAINS => ->(other_value, self_value) { !other_value&.include? self_value },
+          REGEX => ->(other_value, self_value) { other_value&.match? self_value }
         }.freeze
 
         def initialize(operator:, value:, property: nil)