[help] to show error messages as a list

related to this thread Multiple error messages in vim message history

How can i define g:errorMessageString as a List?
Can anyone help me fix this?

i am using this code in my vimrc
but i don’t know why the errors don’t show as a list

set autoread
autocmd FocusGained,BufEnter,CursorHold,CursorHoldI * if mode() != 'c' | checktime | endif
autocmd FileChangedShellPost *
  \ echohl WarningMsg | echom "File " . expand('<afile>') . " changed on disk. Buffer reloaded." | echohl None

function! LocalError(err)
    " Update the errorMessageString
    let g:errorMessageString = a:err
    execute 'autocmd VimEnter * echohl ErrorMsg | echomsg' string(g:errorMessageString) '| echohl None'

I hate to manually type :messages to see All those messages