I am using Timber/Twig.
When I create a variable “acf” http://m.pixshare.pro/2018-12-08_2322.png and use it in the twig I get fatal error: Call to a member function has_setting() on array
I can smell bad code here: http://m.pixshare.pro/2018-12-08_2325.png Very poor approach to get acf instance! Please fix this issue.
It’s possible that the $context already contains an ACF object with the key acf and your code overwrites it. This will then destroy any subsequent use of $context['acf'] which Timber (or your Theme) needs.
Try using a different key in your own code ($context['my_acf']) and see whether that helps, or just do a var_dump of $context['acf'] before the first line of code in your example, to see whether it already exists. Timber objects/context already have a lot of data in them, which you might not know already exists.