Description:
------------
In the current implementation, there is no explicit return type behaviour for the createfromformat method.
There 3 states:
* everything ok and createfromformat return object
* error, when createfromformat return false
* warning, return object but need do extra check with method getLastErrors


possible solutions:
* change behaviour for createfromformat in next release. make warnings as errors and return false if any warning happens
* change documentation. add information about getLastErrors method, add example for getLastErrors to page https://www.php.net/manual/en/datetime.createfromformat.php, fix Return Values description

Test script:
---------------
<?php
//https://3v4l.org/JqSuG

$datetime = \DateTimeImmutable::createFromFormat('m.d.Y', '23.06.2020');

var_dump($datetime);
var_dump($datetime === false); //Return Values: false on failure 
var_dump(\DateTimeImmutable::getLastErrors()); //The parsed date was invalid

$datetime = \DateTimeImmutable::createFromFormat('d.m.Y', '23.06.2020');

var_dump($datetime);
var_dump($datetime === false);
var_dump(\DateTimeImmutable::getLastErrors());