[Bug]: NPE in currentPageState when multiple collaborators in a room
### What happened?

@judicaelandria reports that, when there are multiple people in a room (maybe 30+), there is an NPE with the page state being missing.

![Image](https://github.com/user-attachments/assets/2bbad646-1ad0-428a-a634-ac72beb52323)

I'm wondering, this is a stab in the dark, whether this is related to https://github.com/tldraw/tldraw/pull/5211 which also is an NPE when there are multiple collaborators.

### How can we reproduce the bug?

_No response_

### What browsers are you seeing the problem on?

_No response_

### Where did this happen?

The developer package

### Contact Details

_No response_

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