Add test column fix

autoload/flog/test.vim

@@ -11,21 +11,28 @@ endfunction
 function! flog#test#ShowNvimBufHl() abort
   " Get all highlight group extmarks
   let l:line_hl_groups = {}
+  let l:col_fix = v:null
   for [l:id, l:row, l:start_col, l:details] in nvim_buf_get_extmarks(
         \ 0, -1, 0, -1, { 'details': 1, 'type': 'highlight' })
     if !has_key(l:line_hl_groups, l:row)
       let l:line_hl_groups[l:row] = {}
     endif
     let l:hl_groups = l:line_hl_groups[l:row]
 
+    " Fix bug in old versions of Neovim where start_col is off by one
+    if l:col_fix == v:null
+      let l:col_fix = l:start_virtcol > 0
+    endif
+    if l:col_fix
+      let l:start_col -= 1
+    endif
+
     let l:start_virtcol = virtcol([l:row + 1, l:start_col])
     let l:end_virtcol = virtcol([l:row + 1, l:details.end_col]) - 1
 
-    if l:end_virtcol >= l:start_virtcol
-      for l:virtcol in range(l:start_virtcol, l:end_virtcol)
-        let l:hl_groups[l:virtcol] = l:details.hl_group
-      endfor
-    endif
+    for l:virtcol in range(l:start_virtcol, l:end_virtcol)
+      let l:hl_groups[l:virtcol] = l:details.hl_group
+    endfor
   endfor
 
   " Build output