[HttpFoundation] work around PHP 7.3 bug related to json_encode()

Author: nicolas-grekas

Descriptor/JsonDescriptor.php

@@ -97,7 +97,14 @@ protected function describeApplication(Application $application, array $options
      */
     private function writeData(array $data, array $options)
     {
-        $this->write(json_encode($data, isset($options['json_encoding']) ? $options['json_encoding'] : 0));
+        $flags = isset($options['json_encoding']) ? $options['json_encoding'] : 0;
+
+        if (\PHP_VERSION_ID >= 70300 && (JSON_THROW_ON_ERROR & $flags)) {
+            // Work around https://bugs.php.net/77997
+            json_encode(null);
+        }
+
+        $this->write(json_encode($data, $flags));
     }
 
     /**