Fix symbolication for frames without filename

Summary: Metro server would fail when frame.file would be null. This can happen when the frame is not in js.

Reviewed By: davidaurelio

Differential Revision: D8055637

fbshipit-source-id: eed5abe0cacef68b72a1cd47db23426b5c594727

packages/metro/src/Server.js

@@ -945,6 +945,7 @@ class Server {
           // does not need to symbolication.
           // Skip anything except http(s), because there is no support for that yet
           if (
+            sourceUrl != null &&
             !urls.has(sourceUrl) &&
             !sourceUrl.endsWith('/debuggerWorker.js') &&
             sourceUrl.startsWith('http')