Treat an empty string as invalid JSON, as PHP 7 always does.

src/HttpConverter.php

@@ -3,7 +3,6 @@
 namespace Crell\ApiProblem;
 
 use Psr\Http\Message\ResponseInterface;
-use Zend\Diactoros\Stream;
 
 /**
  * Utility class to convert a problem object to an HTTP Response, using PSR-7.
@@ -42,10 +41,8 @@ public function __construct($pretty = false)
     public function toJsonResponse(ApiProblem $problem, ResponseInterface $response)
     {
         $body = $response->getBody();
-        $body->rewind();
         $body->write($problem->asJson($this->pretty));
 
-
         return $this->toResponse($problem, $response)
             ->withHeader('Content-Type', 'application/problem+json')
             ->withBody($body);
@@ -64,16 +61,12 @@ public function toJsonResponse(ApiProblem $problem, ResponseInterface $response)
      */
     public function toXmlResponse(ApiProblem $problem, ResponseInterface $response)
     {
-        // @todo Figure out why Diactoros' stream implementation isn't handling
-        // this for us, and for that matter is there a way to avoid relying on
-        // Diactoros?
-        $stream = fopen('php://temp', 'w');
-        fwrite($stream, $problem->asXml($this->pretty));
-        rewind($stream);
+        $body = $response->getBody();
+        $body->write($problem->asXml($this->pretty));
 
         return $this->toResponse($problem, $response)
             ->withHeader('Content-Type', 'application/problem+xml')
-            ->withBody(new Stream($stream));
+            ->withBody($body);
     }
 
     /**