Timing bug with Suspense render results in `TypeError: Cannot set property '0' of null.`

The app crash I’m seeing originates from here and surfaced as TypeError: Cannot set property '0' of null.

This was discovered during an application reworking to use preact rather than react. The bug does not repro with react.

Reproduction

CodeSandbox available here Minimal repo showing the issue is available here

Steps to reproduce

Force a re-render of a component hosting the <Suspense /> element before the initial fallback has rendered. In the minimal repro and my case, this was happening because something was being calculated and put into state during componentDidMount.

Suspense thinks it needs to render the fallback and detach the lazy component, however, because of the external re-render, there are no children in the vnode

Expected Behavior

Either the lazy is rerun, or the fallback is rendered.

Actual Behavior

The app crashes with TypeError: Cannot set property '0' of null.

[davidrhoderick]

This shouldn’t be closed (or maybe a new issue should be made) because as of 10.5.14, I get a t.__H is null error. When I downgrade to 10.5.4 as per @imgalli suggests, it goes away.

[iMakedonsky]

@rdalmas there were a couple of issues with suspense.

1. multiple lazy children inside suspense with preact/compat is causing one such bug. Fixed by wrapping only one lazy child inside a Suspense.
2. There is a problem with components triggering onClick callbacks after being unmounted. Fixed by:

import { options } from 'preact';
options.debounceRendering = setTimeout;

1. There are hydrate issues if you’re using ssr/prerendering. Resolved by using preact-iso.lazy/hydrate instead of regular lazy/hydrate