Silence Bluebird's unreturned-Promise warning

src/stream.js

@@ -11,12 +11,12 @@ function wrapStreamHandler(stream, handler, callback, item) {
 		return assureArray(result);
 	}).each((newItem) => {
 		stream.push(newItem);
+
+		// Silence the "a promise was created in a handler at [...] but was not returned from it" Bluebird warning that occurs in the above; that happens because the `.push` will trigger a *different* wrapped stream's handler (essentially a recursive call), and the Promise that `wrapStreamHandler` creates there is disconnected from this chain. That's not a problem because we use `.nodeify` to wire up the error/completion handling, and so the result of this chain doesn't actually get "lost" like Bluebird thinks.
+		return null;
 	}).then(() => {
-		// TODO: Fix the "a promise was created in a handler at [...] but was not returned from it" Bluebird warning that occurs here
-		callback();
-	}).catch((err) => {
-		callback(err);
-	});
+		return;
+	}).nodeify(callback);
 }
 
 module.exports = function stream(handler, flushHandler) {