BigPipe causes PHP notices with JavaScript disabled on error pages

Reproduced. Thanks for the bug report! Working on test + fix.

The root cause is this wrong assumption:

    // It does not make sense to have BigPipe responses for subrequests. BigPipe
    // is never useful internally in Drupal, only externally towards end users.
    $response = $event->getResponse();
    $is_eligible = $event->isMasterRequest() && $response instanceof HtmlResponse;
    $event->getRequest()->attributes->set(self::ATTRIBUTE_ELIGIBLE, $is_eligible);
    if (!$is_eligible) {
      return;
    }

This should also be backported to https://www.drupal.org/project/big_pipe.

#2652766: PHP notice on page not found (when JS is disabled) was opened long before this, but the steps to reproduce were missing there. Berdir just reopened it with STR basically identical to this one. I closed that as a duplicate of this one.

Thanks for the reference, somehow I only found the old issue, not this one.

Note that interestingly, I only got a single notice for 2, not 1. Although manual debugging showed that the explode only returned an array with a single key. I'll test this tomorrow.

I also don't have JS disabled, but maybe the issue title isn't correct about that?

I think #12 is alluding to it, but I'll spell it out explicitly for #11: @Berdir, perhaps you don't have JS disabled, but you still have the BigPipe no-JS cookie?

Confirmed, this fixes it for me as well.

Perfect :)

RTBC + 1

Less complexity and more tests - nice!

Committed 30cf748 and pushed to 8.1.x and 8.2.x. Thanks!

Also committed & pushed to the contrib module for Drupal 8.0: http://drupalcode.org/project/big_pipe.git/commit/f0a2205.

This isn't really fully fixed yet.

I created a module that takes data driven by linkchecker and does requests using Javascript that check for broken links on a site, it makes requests as fast as ajax can get the headers, doing this causes a zillion of these messages:

Notice: Undefined offset: 1 in Drupal\big_pipe\Render\BigPipe->sendPreBody() (line 333 of core/modules/big_pipe/src/Render/BigPipe.php).
Notice: Undefined offset: 2 in Drupal\big_pipe\Render\BigPipe->sendPreBody() (line 333 of core/modules/big_pipe/src/Render/BigPipe.php).

Fix is inspired by this idea:
https://stackoverflow.com/a/56971347

see patch:

created a new issue for this, triggered tests and they all pass.

#3194462: BigPipe when server under heavy load results in PHP notices

Fix patch from #22 to drupal 9.5

upd

Warning: Undefined array key 1 in Drupal\big_pipe\Render\BigPipe->sendPreBody() (line 311 of core/modules/big_pipe/src/Render/BigPipe.php).

Drupal\big_pipe\Render\BigPipe->sendPreBody() (Line: 282)
Drupal\big_pipe\Render\BigPipe->sendContent() (Line: 113)
Drupal\big_pipe\Render\BigPipeResponse->sendContent() (Line: 423)
Symfony\Component\HttpFoundation\Response->send() (Line: 20)

Original Text : Après avoir cherché en profondeur la cause possible de l’erreur, il se peut que certaines extensions de navigateur qui injectent du code dans l’en-tête de la page provoquent une erreur avec BigPipe. Essayez de désactiver certaines extensions de votre navigateur pour identifier laquelle pose problème.

After thoroughly investigating the possible cause of the error, it may be that some browser extensions that inject code into the page head tag are causing an error with BigPipe. Try disabling certain extensions in your browser to identify which one is causing the problem.