vim:funcs: Silence checktime call

The checktime command is not available in the command line window. As
the `CheckTime` function runs every second, the command line window
spits out an error message every second making it practically unusable.

This patch silences the `checktime` call to fix this.

.config/vim/vimrc.d/70-functions.vim

@@ -11,7 +11,9 @@ endfunction
 " Check time every second to read file changes.
 if (exists('+autoread') && &autoread)
 	function! CheckTime(timer)
-		checktime
+		" NOTE: silent the checktime call as it is an invalid command in the
+		" command line window
+		silent! checktime
 	endfunc
 	execute timer_start(1000, 'CheckTime', {'repeat': -1})
 endif