Sorry I thought that we need to check $n first.

The Kata definition is: Build a function that returns an array of integers from n to 1 where n>0.

You need to check first if $n is greater than 0

Literally forgot I could have used a ternery operator :facepalm:

Fixed

In addition to what @Dec0y-jb said, It's also takes advantage of what PHP considers "truthy" and "falsey". To learn more about what PHP considers "true", see the truth table in the documentation.
http://php.net/manual/en/types.comparisons.php

Here, the code array_sum($a) % 2 returns an integer number. If it returns any number other than 0, the ternary operator sees it as a "true" condition, thereby returning the first value. However, if it returns exactly 0, the ternary operator sees it as a "false" condition, returning the second value.

I've never understood these ternery operators :/

Why "-2.478002 -2.65651 -2.389484 0.453677 +" is equal 0.1785082 on random test(PHP)?

Must have gotten lucky is the 2 test cases checked against (50/50 in this case);
min() is just as likely. Still possible to use both of them together for a one-liner ternary though to be more complete.

How does this one work?

Your code seems like efficient! because array_pop reduces the size of array. It's cool :)