Can't reproduce with current 7.4 HEAD.

Can reproduce with opcache ... didn't know that's enabled on Travis.

Heh, this is a stack overflow caused by infinite recursion in the error handler for a "Trying to access array offset on value of type null" notice.

The original notice is triggered in https://github.com/Seldaek/monolog/blob/21b1705c3e6a6312687a275870e3e539af0a3896/src/Monolog/Handler/ElasticsearchHandler.php#L150 and the infinite recursion occurs in https://github.com/Seldaek/monolog/blob/21b1705c3e6a6312687a275870e3e539af0a3896/src/Monolog/ErrorHandler.php#L201.

Not sure where the opcache-specific bit in this is.

@seld: The problematic error handler is set up here: https://github.com/Seldaek/monolog/blob/21b1705c3e6a6312687a275870e3e539af0a3896/tests/Monolog/ErrorHandlerTest.php#L40-L42

So while there is presumably also an opcache bug here that causes the notice in the first place, this code should probably also be fixed to make sure that any notice thrown in the testsuite does not automatically turn into a stack overflow segfault.

Ok thanks for the find. I fixed it in https://github.com/Seldaek/monolog/commit/0f39561898a66334fe5f2a6768eb8043d2f34cd5 which fixes the build. 

It seems to pass without notice either so I am not sure how this is possible. If opcache caused the notice which then crashed with the segfault the notice should still be there. If opcache had only an issue with the error handler then it should show a notice now?

@seld: If I patch https://github.com/Seldaek/monolog/blob/a053af62ad5bfb0355dfb55d3d15126f1c836708/src/Monolog/Handler/ElasticsearchHandler.php#L148 to throw an exception if $responses is null, then I do get that exception. So the notice should also be thrown -- there's probably still an error handler around that suppresses it.

That said, I get the null value there both with and without opcache, so I'm not sure what the role of opcache was here originally...

Closing this as the original issue was resolved...