Don't break the trace (#11311)

Closes #11311

COPYBARA_INTEGRATE_REVIEW=https://github.com/protocolbuffers/protobuf/pull/11311 from umpirsky:patch-1 d280be57b7
PiperOrigin-RevId: 603963886

php/src/Google/Protobuf/Internal/Message.php

@@ -1314,7 +1314,7 @@ class Message
         try {
             $this->mergeFromJsonArray($array, $ignore_unknown);
         } catch (\Exception $e) {
-            throw new GPBDecodeException($e->getMessage());
+            throw new GPBDecodeException($e->getMessage(), $e->getCode(), $e);
         }
     }