Local change is not updating in the counter example

[chacha912]

What happened:

Local change is not updated in the counter example.

What you expected to happen:

When the increment button is clicked, the counter value should also update on the local.

How to reproduce it (as minimally and precisely as possible):

1. Run npm run dev and open http://localhost:9000/counter.html in your browser
2. Click + button to increment the counter
3. The changes are applied to both the local and remote
   -> currently, the doc.getRoot().counter value does not change on the local
4. Refreshing will update the counter value as expected.

Anything else we need to know?:

Environment:

• Operating system:
• Browser and version:
• Yorkie version (use yorkie version): 0.2.20
• Yorkie JS SDK version: 0.2.20