Ignore stale replies

Summary: Changelog: ignore stale replies

Reviewed By: lblasa

Differential Revision: D32829739

fbshipit-source-id: 267f43f8e8f3dea60ee86187f7a7709fea09e5af

desktop/flipper-server-core/src/comms/BrowserServerWebSocket.tsx

@@ -97,6 +97,11 @@ class BrowserServerWebSocket extends SecureServerWebSocket {
           // Upon initialization it sent a `getPlugins` request.
           // We find that request and resolve it with the list of plugins we received from the `connect` message
           const getPluginsCallbacks = clientConnection.matchPendingRequest(0);
+
+          if (!getPluginsCallbacks) {
+            return;
+          }
+
           getPluginsCallbacks.resolve({
             success: {plugins},
             length: rawMessage.length,