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)

" Vim filetype plugin file
" Language:             calendar(1) input file
" Previous Maintainer:  Nikolai Weibull <now@bitwi.se>
" Latest Revision:      2008-07-09

if exists("b:did_ftplugin")
  finish
endif
let b:did_ftplugin = 1

let s:cpo_save = &cpo
set cpo&vim

let b:undo_ftplugin = "setl com< cms< inc< fo<"

setlocal comments=s1:/*,mb:*,ex:*/ commentstring& include&
setlocal formatoptions-=t formatoptions+=croql

let &cpo = s:cpo_save
unlet s:cpo_save