Async routes cause warning when using `preact/debug`

[jgierer12]

Do you want to request a feature or report a bug?
Bug

What is the current behavior?
When using preact/debug as recommmended in the Preact readme, async routes cause the following warning to appear in the browser console:

Undefined component passed to preact.h()
<undefined path="/" url="/" matches="[object Object]" /> debug.js:17

The routes still work perfectly fine, but the warning is misleading and confusing.

I'm not sure if this is a bug in preact-cli's async loading strategy or preact itself, but I suspect the former.

If the current behavior is a bug, please provide the steps to reproduce.

1. preact create default test
2. cd test, npm install
3. Edit src/components/app.js as follows:

 import { Router } from 'preact-router';
 
+if (module.hot) {
+	require('preact/debug');
+}
+
 import Header from './header';

4. npm run start, open http://localhost:8080, open console with Ctrl+Shift+K (or your OS and browser's equivalent)
5. The above warning will appear in the console

What is the expected behavior?
No warning should be shown since everything works as expected

Please mention other relevant information.

• node version 8.9.1
• npm version 5.6.0
• Operating system Windows 10 1709

[alvis]

I also received the warning Undefined component passed to preact.h(), and therfore I am here. I'm not sure if the message is misleading, as there is indeed an undefined component. However, it appears to be a bug to begin with and should be properly handled.

[dsky1990]

same problem
Undefined component passed to preact.h() <undefined path="/" url="/" matches="[object Object]" />
debug.js?834f:17

[dsky1990]

also happen in router changed

[divyanshutomar]

I am facing the same issue even if the route is not async.

[jgierer12]

@divyanshutomar I think all routes are async by default

[XavierLeTohic]

+1

[ForsakenHarmony]

That was not intentional, sorry

But yes all routes in src/routes are async by default

[joaocunha]

I still get this error if I run preact watch but not if I run npm run start.

[lukeed]

@joaocunha are you sure that both your local and global installations (if any) are up to date?

[joaocunha]

I am. Can't properly replicate, tho - it's intermitent. I'll try more and update this issue.