$data Unsupported operand types error fix

the operator `+=` only works like `array_merge ($left, $right) ;` if both variables are arrays

Author: gabidj

examples/01-blog/graphql.php

@@ -36,9 +36,18 @@
     if (isset($_SERVER['CONTENT_TYPE']) && strpos($_SERVER['CONTENT_TYPE'], 'application/json') !== false) {
         $raw = file_get_contents('php://input') ?: '';
         $data = json_decode($raw, true);
+        // $data += will cause 'Unsupported operand types' Fatal error on `null`
+        // check if decoded data is an array (or stdobject) - not null
+        // if any kind of data is present we don't want to lose it
+        if ($data === null) {
+            $data = [];
+        }
     } else {
         $data = $_REQUEST;
     }
+    
+
+    
     $data += ['query' => null, 'variables' => null];
 
     if (null === $data['query']) {