Expected result: Throwing an exception with message "Call to undefined function ttt()".
Actual result: Connection reset by peer => 502 Bad Gateway.

Additional examples:
try {
eval('ttt();');
echo 'OK';
} catch (Error $e) {
echo $e->getMessage(); // "Call to undefined function ttt()"
}
exit(0);

Actual result: "Call to undefined function ttt()".
Expected result: "Call to undefined function ttt()".

try {
eval('ttt();');
echo 'OK';
} catch (Error $e) {
echo $e->getMessage();
throw $e; // Connection reset by peer => 502 Bad Gateway
}
exit(0);

Actual result: Connection reset by peer => 502 Bad Gateway.
Expected result: Throwing an exception with message "Call to undefined function ttt()".

Conclusion: an exception is thrown, but if it is not caught, the php process crashes.