patch 8.1.0747: map() with a bad expression doesn't give an error commit https://github.com/vim/vim/commit/ce9d50df07402cb8e196537a9c4505845adecabc Author: Bram Moolenaar <Bram@vim.org> Date: Mon Jan 14 22:22:29 2019 +0100 patch 8.1.0747: map() with a bad expression doesn't give an error Problem: map() with a bad expression doesn't give an error. (Ingo Karkat) Solution: Check for giving an error message. (closes https://github.com/vim/vim/issues/3800)