each() is deprecated as of PHP 7.2.0

[MHimken]

cssmin/libs/CssMin.php

Line 2223 in 9a69350

while (list($i, $path) = each($paths))

Changing this line from each() to foreach()
Old line
while (list($i, $path) = each($paths))
New line
foreach ($paths as $i=>$path)
This method is also a lot faster. See https://www.php.net/manual/en/function.each.php