vim filters and stdout/stderr

You can use Python to distinguish between stdout and stderr:

python import vim, subprocess
python b=vim.current.buffer
python line=vim.current.range.start
python p=subprocess.Popen(["command", "argument", ...], stdout=subprocess.PIPE, stderr=subprocess.PIPE, close_fds=True)
python returncode=p.poll()
python if not returncode: b.append(("STDOUT:\n"+p.stdout.read()+"\nSTDERR:\n"+p.stderr.read()).split("\n"), line)

:!{cmd} Executes {cmd} with the shell and sets v:shell_error.

If you happen to set up mappings to call your filters, you could do something like the following:

function! UndoIfShellError()
    if v:shell_error
        undo
    endif
endfuntion

nmap <leader>filter :%!/path/to/filter<CR>:call UndoIfShellError()<CR>