patch 8.2.3911: Vim9: type check for filter() does not accept unknown Commit: https://github.com/vim/vim/commit/ef8f04b1d1daf2e0be8fa38dedcae84ebfc5ffb4 Author: Bram Moolenaar <Bram@vim.org> Date: Mon Dec 27 12:29:19 2021 +0000 patch 8.2.3911: Vim9: type check for filter() does not accept unknown Problem: Vim9: type check for filter() does not accept unknown. Solution: Also accept unknown for the return type. (closes https://github.com/vim/vim/issues/9413)