[Bundle] Rendering unknown attachment should not turn blank

[compulim]

Screenshots

Version

R12 candidate

Describe the bug

When using webchat*.js, it load React 16.8.6 internally.

When rendering attachments with error, such as the unknown attachment command, we didn't catch that exception in <ErrorBoundary>. Thus the uncaught exception bubble up to React and triggered a bug in React, causing hooks to collapse catastrophically.

It was fixed in React 16.11 (or lower). Instead of bumping React, we prefer to keep the internal React to 16.8.6.

Like other middleware, we should use <ErrorBoundary> (or the friendlier <UserlandBoundary>) to wrap around components that have potential to break Web Chat.

This issue should have caught earlier, but we missed a test for unknown attachment command.

Steps to reproduce

1. Use webchat*.js to load Web Chat
2. Talk to MockBot
3. Type unknown attachment

Expected behavior

It should show a red box or console error in production mode. Or a red box in development mode.

Additional context

[Bug]