After talking with guys from PhpStorm it appears, that XDebug might not be providing such info at all. So if a line of code gets executed during step-by-step debugging and it produces an error (or several) in a result, then nothing is returned by xdebug to show that in Console.

Zend Debugger somehow managed to implement this and this is very helpful to see an error happening real time after it happens during debugger.

I've added the following to the PhpStorm issue. I don't think we need to add this though, as PhpStorm allows Notice/Warning breakpoints, that do the same thing now.

Dear PhpStorm developers, and in specific @Svetlana.Zemlyanskaya - is this something you find interesting to add to PhpStorm? In the debugging protocol, I would have to add a new [notification|https://xdebug.org/docs-dbgp.php#notifications], for example:

{code}
<notification xmlns="urn:debugger_protocol_v1" xmlns:xdebug="http://xdebug.org/dbgp/xdebug" name="debug">
<xdebug:type>Warning</xdebug:type>
<xdebug:location
filename="file:///C:/Users/Nikolay.Matveev/Test/phpstorm/script_debug_test/wi5927.php"
lineno="2"/>
<xdebug:message><![CDATA[Undefined variable $x]]></xdebug:message>
</notification>
{code}

Of course, this is already sort of possible to achieve by setting a Notice or Warning breakpoint. I think PhpStorm already does this by default, which makes this feature moot...

I was aware of Notice/Warning breakpoints, but they aren't much useful, because:

1. you can't define them globally and have to specify them in each project you open
2. no actual notice/warning message is shown and therefore I have to guess what might have gone wrong

OK, I've added a comment to https://youtrack.jetbrains.com/issue/WI-13369 too.

I have written to the DBGp development list with an RFC for the addition to the specification: https://xdebug.org/archives/xdebug-dev/2641.html

A preliminary Xdebug implementation is in a PR at https://github.com/xdebug/xdebug/pull/310

Fixed in GIT - thanks for playing! :-)