Ensure that FeatureFlag _rules is non-null

Author: arun251

src/LaunchDarkly/FeatureFlag.php

@@ -60,7 +60,7 @@ public static function getDecoder() {
                 array_map(Prerequisite::getDecoder(), $v['prerequisites'] ?: []),
                 $v['salt'],
                 array_map(Target::getDecoder(), $v['targets'] ?: []),
-                array_map(Rule::getDecoder(), $v['rules']),
+                array_map(Rule::getDecoder(), $v['rules'] ?: []),
                 call_user_func(VariationOrRollout::getDecoder(), $v['fallthrough']),
                 $v['offVariation'],
                 $v['variations'],