Fix an invalid array access and enable CI for PHP 7.4

Author: fd-automox

.travis.yml

@@ -9,6 +9,7 @@ stages:
 php:
   - '7.2'
   - '7.3'
+  - '7.4'
 
 before_script:
   - java -Djava.library.path=./DynamoDBLocal_lib -jar dynamodb_local/DynamoDBLocal.jar --port 3000 &

src/ConditionAnalyzer/Analyzer.php

@@ -204,10 +204,13 @@ private function hasValidQueryOperator($hash, $range = null)
         $validQueryOp = ComparisonOperator::isValidQueryDynamoDbOperator($hashCondition['type'] ?? null);
 
         if ($validQueryOp && $range) {
-            $rangeCondition = $this->getCondition($range);
+            $rangeConditionType = $this->getCondition($range)['type'] ?? null;
+            if ($rangeConditionType === null) {
+                return false;
+            }
 
             $validQueryOp = ComparisonOperator::isValidQueryDynamoDbOperator(
-                $rangeCondition['type'],
+                $rangeConditionType,
                 true
             );
         }