Content script doesn't load in srcdoc iframes causes message retries

[twschiller]

Context

• See comment/screenshot here: https://github.com/pixiebrix/pixiebrix-extension/pull/6198#issuecomment-1663880196

Steps to Reproduce

• Turn on WEBEXT_MESSENGER_LOGGING=true
• Visit: https://developer.mozilla.org/en-US/docs/Web/HTML/Element/iframe
• Add a Log to Console Brick with "All Frames" and run from the Trigger from the Page Editor

Screenshots

There are multiple "received in content script messages" after the content script responds

Discussion

There might be extra copies of the content script in top-level frame. (But only one of them has any logs in the console for the context). I think these were injected by the Page Editor

It looks like it's the srcdoc frame, what's interesting is that the brick is not actually being run there though (there's no "Hello" message)

[fregante]

I think these were injected by the Page Editor

I don’t think that’s possible anymore, right? The injection is entirely handled by the browser now. There’s no chance that scrips are injected twice (unless the extension is reloaded). The duplicates you see are probably only due to the dev reload.

What does it look like in the background page? My guess is that each of those message has a sender in the background page

[fregante]

The messages are multiple retries of the same message from the background script, this can be also seen in the background:

I'm having a hard time debugging this issue because the developer tools appear to ignore the breakpoints in that iframe 🤔

My best guess at the moment is that the application is triggering a silent fatal error and the message doesn't even get to respond with that error. My second guess is that the error happens earlier than the method registration, so the code reaches "No handler registered" and moves forward as a "retriable scenario"

[fregante]

As you mentioned before, all the http checks in the app should at least be updated to include about:, for example:

https://github.com/pixiebrix/pixiebrix-extension/blob/294337ff7761eb4561a610b0df33c0741d267410/src/permissions/permissionsUtils.ts#L184C1-L186

[fregante]

Indeed no methods are being registered in that context:

So it causes this error:

[fregante]

contentScriptCore: init is not in the console, probably import("contentScriptCore") is failing entirely

https://github.com/pixiebrix/pixiebrix-extension/blob/294337ff7761eb4561a610b0df33c0741d267410/src/contentScript/contentScriptCore.ts#L51C1-L54

Is the @cfworker/json-schema error related? new URL('about:srcdoc').origin === 'null' so this is probably breaking a lot of expectations everywhere. I can work on this issue until it's resolved if you confirm.

https://github.com/pixiebrix/pixiebrix-extension/assets/1402241/b9b7f451-6ce3-4aaa-8733-f77e3f6e1365

[twschiller]

Since it's a module-level import, you're right it'd be preventing the contentScript entry point from loading

Here's the code: https://github.com/cfworker/cfworker/blob/main/packages/json-schema/src/dereference.ts#L68

Would be great if you could create an issue/PR in the cfworker repo. We will likely have to vendor that file in the meantime and swap it out via webpack alias

[fregante]

I just noticed that this is still open and assigned to me. If it's still an issue even after that PR I can keep looking into it

[twschiller]

Thank you for checking, I think we just forgot to close it. Closing now