Hello,

the line

leads to an error message

line    4:
/c/\12
line    5:
E65: Illegal back reference

as shown by

let fname = '/c/\12'
let fname = fnamemodify(fname, ":p")
let fname = glob(fname)

if v:oldfiles contains file paths with back and forward slashes (as happens when using Vim in MSYS2 and Windows).

Maybe the slashes should be all converted to \

if exists('+shellslash') && !&shellslash

and to / otherwise?