add a few checks for safety

lib/storage/file.js

@@ -59,7 +59,8 @@ var channelExists = function (filepath, cb) {
 };
 
 const destroyStream = function (stream) {
-    stream.close();
+    if (!stream) { return; }
+    try { stream.close(); } catch (err) { console.error(err); }
     setTimeout(function () {
         try { stream.destroy(); } catch (err) { console.log(err); }
     }, 5000);