[PHP] Better handling of invalid data (array) (#6760)

* Update ObjectSerializer.mustache

If the $data is a wrongly formatted Json or if data is not an array, php gives error:

Invalid argument supplied for foreach() at line 257 (Now line is 262)

* update samples

Co-authored-by: William Cheng <wing328hk@gmail.com>

modules/openapi-generator/src/main/resources/php/ObjectSerializer.mustache

@@ -252,6 +252,11 @@ class ObjectSerializer
             return null;
         } elseif (strcasecmp(substr($class, -2), '[]') === 0) {
             $data = is_string($data) ? json_decode($data) : $data;
+            
+            if (!is_array($data)) {
+                throw new \InvalidArgumentException("Invalid array '$class'");
+            }
+
             $subClass = substr($class, 0, -2);
             $values = [];
             foreach ($data as $key => $value) {

samples/client/petstore/php/OpenAPIClient-php/lib/ObjectSerializer.php

@@ -262,6 +262,11 @@ public static function deserialize($data, $class, $httpHeaders = null)
             return null;
         } elseif (strcasecmp(substr($class, -2), '[]') === 0) {
             $data = is_string($data) ? json_decode($data) : $data;
+
+            if (!is_array($data)) {
+                throw new \InvalidArgumentException("Invalid array '$class'");
+            }
+
             $subClass = substr($class, 0, -2);
             $values = [];
             foreach ($data as $key => $value) {