Code spell checker extension crashes extension host

[JonasHelming]

The spell checker extension seems to continuously throw errors, bringing down the extension host. This then also crashes other features such as TypeScript support. We should check whether this can be reliably reproduced. If yes, I would triage this as a blocker, as the extension is very popular. (streetsidesoftware.code-spell-checker)
@tsmaeder Could you see whether this occurs to you by using the extension, please?

[sdirix]

When using the spell checker in the Theia IDE 1.60.0, after some time my console is flooded with errors like this:

plugin-host ERROR TypeError: r is not iterable
    at u (/home/user/.theia-ide/deployedPlugins/streetsidesoftware.code-spell-checker-4.0.42/extension/packages/client/dist/extension.cjs:447:36482)
    at f (/home/user/.theia-ide/deployedPlugins/streetsidesoftware.code-spell-checker-4.0.42/extension/packages/client/dist/extension.cjs:447:36526)
    at /tmp/.mount_TheiaISBqPtc/resources/app/lib/backend/638.js:2:125967
    at s.invoke (/tmp/.mount_TheiaISBqPtc/resources/app/lib/backend/638.js:2:126057)
    at a.fire (/tmp/.mount_TheiaISBqPtc/resources/app/lib/backend/638.js:2:127860)
    at t.TabsExtImpl.$acceptTabOperation (/tmp/.mount_TheiaISBqPtc/resources/app/lib/backend/339.js:1:376476)
    at t.RPCProtocolImpl.handleRequest (/tmp/.mount_TheiaISBqPtc/resources/app/lib/backend/366.js:1:153485)
    at c.requestHandler (/tmp/.mount_TheiaISBqPtc/resources/app/lib/backend/366.js:1:153056)
    at c.handleRequest (/tmp/.mount_TheiaISBqPtc/resources/app/lib/backend/638.js:2:17249)
    at c.handleMessage (/tmp/.mount_TheiaISBqPtc/resources/app/lib/backend/638.js:2:15151)

[tsmaeder]

I would triage this as a blocker,

I would not hold up the release for this issues as it's very likely no worse than before. We have not touched the tabs API in months.

[tsmaeder]

Also I'm getting a different batch of stack traces:

logger-protocol.ts:118 2025-04-01T07:39:31.413Z plugin-host ERROR TypeError: r is not iterable
    at u (C:\Users\thomas\.theia-ide\deployedPlugins\streetsidesoftware.code-spell-checker-4.0.42\extension\packages\client\dist\extension.cjs:447:36482)
    at C:\Users\thomas\.theia-ide\deployedPlugins\streetsidesoftware.code-spell-checker-4.0.42\extension\packages\client\dist\extension.cjs:447:36746
    at kg._notifySubscriber (C:\Users\thomas\.theia-ide\deployedPlugins\streetsidesoftware.code-spell-checker-4.0.42\extension\packages\client\dist\extension.cjs:469:1251)
    at kg._notify (C:\Users\thomas\.theia-ide\deployedPlugins\streetsidesoftware.code-spell-checker-4.0.42\extension\packages\client\dist\extension.cjs:469:1366)
    at kg.notify (C:\Users\thomas\.theia-ide\deployedPlugins\streetsidesoftware.code-spell-checker-4.0.42\extension\packages\client\dist\extension.cjs:469:1581)
    at kg.notify (C:\Users\thomas\.theia-ide\deployedPlugins\streetsidesoftware.code-spell-checker-4.0.42\extension\packages\client\dist\extension.cjs:469:2061)
    at Ig.handleDiagsFromServer (C:\Users\thomas\.theia-ide\deployedPlugins\streetsidesoftware.code-spell-checker-4.0.42\extension\packages\client\dist\extension.cjs:475:8367)
    at C:\Users\thomas\.theia-ide\deployedPlugins\streetsidesoftware.code-spell-checker-4.0.42\extension\packages\client\dist\extension.cjs:475:6938
    at C:\Users\thomas\AppData\Local\Programs\TheiaIDE\resources\app\lib\backend\638.js:2:125967
    at s.invoke (C:\Users\thomas\AppData\Local\Programs\TheiaIDE\resources\app\lib\backend\638.js:2:126057)
```
There doesn't really be any or our code on the code path here.

[tsmaeder]

@sdirix I can't really imagine how an extension should bring down the extension host except by using too much memory. Could you maybe try and up the limit for nodejs?

[JonasHelming]

@sdirix I can't really imagine how an extension should bring down the extension host except by using too much memory. Could you maybe try and up the limit for nodejs?

So you are getting the errors, but it does not crash for you, correct?

[tsmaeder]

Yes, I've been running with the extension for > 1hour with no discernible ill effects. That's on Windows, I suspect @sdirix is running on Linux?

[sdirix]

What happens for me is that the Typescript language features stop working after 10-15 minutes of use, i.e. they no longer update. Then the console is flooded with the errors above.

Since I uninstalled the spell checker, the Typescript language features did not stop working for me. When I installed the spell checker again, the Typescript language features crashed again.

Of course this could be an unlucky coincidence, or there is a deeper root cause why running the spell checker obstructs the language features.

I'm running on Ubuntu 24.04 with the Theia IDE preview channel.

[tsmaeder]

Using oodles of memory might very well resource-constrain the other extensions running in the extension host.