NullException when creating NetworkException (#403)

* NullException when creating NetworkException

* Make sure we use the proper error handling

Co-authored-by: Nyholm <tobias.nyholm@gmail.com>

lib/Client/FileGetContents.php

@@ -22,9 +22,10 @@ public function sendRequest(RequestInterface $request, array $options = []): Res
         $content = file_get_contents($request->getUri()->__toString(), false, $context);
         error_reporting($level);
         if (false === $content) {
-            $error = error_get_last();
-
-            throw new NetworkException($request, $error['message']);
+            if ($error = error_get_last()) {
+                throw new NetworkException($request, $error['message']);
+            }
+            throw new NetworkException($request, 'Failed to get contents from '.$request->getUri()->__toString());
         }
 
         $requestBuilder = new ResponseBuilder($this->responseFactory);