r3f v9 (react 19) error in Effectcomposer

[chrisweb]

I created a reproduction repository for an error in the react postprocessing effectcomposer when using the latest r3f v9 beta 1 package (as well as next.js 15 / react 19)

The error message that gets catched by Next.js is the following:

TypeError: Cannot read properties of undefined (reading 'length')

which corresponds to line 139 https://github.com/pmndrs/react-postprocessing/blob/master/src/EffectComposer.tsx#L139 in the typescript source file

I wasn't sure if this repository is the right place to open an issue, as r3f v9 transitioned to a reconciler (previously core renderer) due to heavy changes in react 19, I assume the problem in the effectcomposer might be related to those changes