Bug: Reaction Button Sample - MockBot not working

Is it an issue related to Adaptive Cards?

No

Is this an accessibility issue?

No

What version of Web Chat are you using?

Latest production

Which distribution are you using Web Chat from?

NPM

Which hosting environment does this issue primarily affect?

Web apps

Which browsers and platforms do the issue happened?

No response

Which area does this issue affect?

Others or unrelated

Which theme pack does this issue affect?

I did not test it on other theme packs

What is the public URL for the website?

No response

Please describe the bug

I am experiencing issues with the reaction button sample.
Specifically:

Reaction Button Sample Throws 502:
The provided mock in the documentation for sending a reaction button from webchat to Azure bot does not work. When attempting to use it, a 502 Bad Gateway error is thrown.

Do you see any errors in console log?

webchat.js:2 - POST https://directline.botframework.com/v3/directline/conversations/FaU3cC3motRFvqzJhTEiE6-us/activities 502 (Bad Gateway)

How to reproduce the issue?

Reaction Button Sample Throws 502:

1. Try out the mock
2. Send a message
3. Observe an error in console log

What do you expect?

No error and possibility to test that functionality.

What actually happened?

The provided mock in the documentation for sending a reaction button from webchat to Azure bot does not work. When attempting to use it, a 502 Bad Gateway error is thrown.

Do you have any screenshots or recordings to repro the issue?

No response

Adaptive Card JSON

No response

Additional context

No response

Start with the reaction-buttons sample at the linked documentation URL and reproduce the failure by sending a message. Inspect the sample's request path and the resulting Direct Line 502 error. Done means the mock can be used to test the reaction button without producing the reported error.