fix(dav): AddExtraHeadersPlugin should not be handled on error

When a request failed (failed upload) the file is not created,
thus this will spam the log with "cannot set extra headers" error.
To reproduce use e.g. files_antivirus with eicar test files.

Signed-off-by: Ferdinand Thiessen <opensource@fthiessen.de>

Author: susnux

apps/dav/lib/Connector/Sabre/AddExtraHeadersPlugin.php

@@ -40,6 +40,11 @@ private function afterPut(RequestInterface $request, ResponseInterface $response
 			return;
 		}
 
+		// skip setting the headers if the PUT request failed
+		if ($response->getStatus() >= 400) {
+			return;
+		}
+
 		$node = null;
 		try {
 			$node = $this->server->tree->getNodeForPath($request->getPath());