Streams crash when attempting to cancel

[aryanjassal]

Describe the bug

When cancelling the web stream using the cancel method, the program crashes with an error saying that readableCancel isn't a valid method - which is weird because doing a console.log(this.readableCancel) returns a valid signature of a function.

This issue was first discovered in Polykey, so the reproduction steps will involve using the application.

To Reproduce

1. Use a RPC handler method - a duplex stream or a client stream
2. Cancel the stream
3. See the error

Expected behavior

The stream should cancel gracefully (while crashing the app works, it is not how it is supposed to cancel the stream)

Logs

Check the comment in additional context for details about the crash and the dissection I performed.

Additional context

• Add cancellation to RPC handlers for the vaults domain Polykey#846 (comment)

Notify maintainers

@CMCDragonkai @tegefaulkes

[linear]

ENG-512 Streams crash when attempting to cancel

[CMCDragonkai]

Can you write a quick code sample that replicates this.

[CMCDragonkai]

Even a test that goes into this repo that repros it, as that would prevent regression.