`expand_tab = false` not working
## Describe the behavior that you expect from SpaceVim
I expected to replace spaces with tabs as a default.
**[This is a mandatory section]**

If possible, in addition to the description, please also provide a link to the relevant SpaceVim documentation that describes the expected behaviour/feature.

## Describe the problem
The problem is that `expand_tab = false` doesn't do anything. [Link](https://spacevim.org/documentation/#code-indentation).
**[This is a mandatory section]**

Please describe the observed problem in simple and clear terms.

## Describe steps to reproduce the problem
Set `expand_tab` to `false` in the spacevim config.
**[This is a mandatory section]**

Please list all the steps from the point the Vim session was started until the problem was observed, in simple and clear terms.

## Debug info
SpaceVim layers:

- VersionControl:       not loaded          https://spacevim.org/layers/VersionControl/
+ autocomplete:             loaded          https://spacevim.org/layers/autocomplete/
- chat:                 not loaded          https://spacevim.org/layers/chat/
+ checkers:                 loaded          https://spacevim.org/layers/checkers/
- chinese:              not loaded          https://spacevim.org/layers/chinese/
- colorscheme:          not loaded          https://spacevim.org/layers/colorscheme/
+ core#banner:              loaded          https://spacevim.org/layers/core/banner/
+ core#statusline:          loaded          https://spacevim.org/layers/core/statusline/
+ core#tabline:             loaded          https://spacevim.org/layers/core/tabline/
+ core:                     loaded          https://spacevim.org/layers/core/
- cscope:               not loaded          https://spacevim.org/layers/cscope/
- ctrlp:                not loaded          https://spacevim.org/layers/ctrlp/
- ctrlspace:            not loaded          https://spacevim.org/layers/ctrlspace/
- debug:                not loaded          https://spacevim.org/layers/debug/
- denite:               not loaded          https://spacevim.org/layers/denite/
+ edit:                     loaded          https://spacevim.org/layers/edit/
- exprfold:             not loaded          no exists
- floobits:             not loaded          https://spacevim.org/layers/floobits/
- foldsearch:           not loaded          https://spacevim.org/layers/foldsearch/
+ format:                   loaded          https://spacevim.org/layers/format/
- fuzzy:                not loaded          no exists
- fzf:                  not loaded          https://spacevim.org/layers/fzf/
- games:                not loaded          no exists
- git:                  not loaded          https://spacevim.org/layers/git/
- github:               not loaded          https://spacevim.org/layers/github/
- gtags:                not loaded          https://spacevim.org/layers/gtags/
- incsearch:            not loaded          no exists
- indentmove:           not loaded          no exists
- japanese:             not loaded          https://spacevim.org/layers/japanese/
- lang#WebAssembly:     not loaded          https://spacevim.org/layers/lang/WebAssembly/
- lang#actionscript:    not loaded          https://spacevim.org/layers/lang/actionscript/
- lang#agda:            not loaded          https://spacevim.org/layers/lang/agda/
- lang#asciidoc:        not loaded          https://spacevim.org/layers/lang/asciidoc/
- lang#aspectj:         not loaded          https://spacevim.org/layers/lang/aspectj/
- lang#assembly:        not loaded          https://spacevim.org/layers/lang/assembly/
- lang#autohotkey:      not loaded          https://spacevim.org/layers/lang/autohotkey/
- lang#batch:           not loaded          https://spacevim.org/layers/lang/batch/
- lang#c:               not loaded          https://spacevim.org/layers/lang/c/
- lang#chapel:          not loaded          https://spacevim.org/layers/lang/chapel/
- lang#clojure:         not loaded          https://spacevim.org/layers/lang/clojure/
- lang#coffeescript:    not loaded          https://spacevim.org/layers/lang/coffeescript/
- lang#crystal:         not loaded          https://spacevim.org/layers/lang/crystal/
- lang#csharp:          not loaded          https://spacevim.org/layers/lang/csharp/
- lang#d:               not loaded          https://spacevim.org/layers/lang/d/
- lang#dart:            not loaded          https://spacevim.org/layers/lang/dart/
- lang#dockerfile:      not loaded          https://spacevim.org/layers/lang/dockerfile/
- lang#eiffel:          not loaded          https://spacevim.org/layers/lang/eiffel/
- lang#elixir:          not loaded          https://spacevim.org/layers/lang/elixir/
- lang#elm:             not loaded          https://spacevim.org/layers/lang/elm/
- lang#erlang:          not loaded          https://spacevim.org/layers/lang/erlang/
- lang#extra:           not loaded          https://spacevim.org/layers/lang/extra/
- lang#factor:          not loaded          no exists
- lang#forth:           not loaded          no exists
- lang#fortran:         not loaded          https://spacevim.org/layers/lang/fortran/
- lang#foxpro:          not loaded          https://spacevim.org/layers/lang/foxpro/
- lang#fsharp:          not loaded          https://spacevim.org/layers/lang/fsharp/
- lang#go:              not loaded          https://spacevim.org/layers/lang/go/
- lang#goby:            not loaded          https://spacevim.org/layers/lang/goby/
- lang#gosu:            not loaded          https://spacevim.org/layers/lang/gosu/
- lang#graphql:         not loaded          https://spacevim.org/layers/lang/graphql/
- lang#groovy:          not loaded          https://spacevim.org/layers/lang/groovy/
- lang#hack:            not loaded          https://spacevim.org/layers/lang/hack/
- lang#haskell:         not loaded          https://spacevim.org/layers/lang/haskell/
- lang#html:            not loaded          https://spacevim.org/layers/lang/html/
- lang#hy:              not loaded          https://spacevim.org/layers/lang/hy/
- lang#idris:           not loaded          https://spacevim.org/layers/lang/idris/
- lang#io:              not loaded          https://spacevim.org/layers/lang/io/
- lang#ipynb:           not loaded          https://spacevim.org/layers/lang/ipynb/
- lang#j:               not loaded          https://spacevim.org/layers/lang/j/
- lang#janet:           not loaded          https://spacevim.org/layers/lang/janet/
- lang#java:            not loaded          https://spacevim.org/layers/lang/java/
- lang#javascript:      not loaded          https://spacevim.org/layers/lang/javascript/
- lang#json:            not loaded          no exists
- lang#julia:           not loaded          https://spacevim.org/layers/lang/julia/
- lang#kotlin:          not loaded          https://spacevim.org/layers/lang/kotlin/
- lang#lasso:           not loaded          https://spacevim.org/layers/lang/lasso/
- lang#latex:           not loaded          https://spacevim.org/layers/lang/latex/
- lang#lisp:            not loaded          https://spacevim.org/layers/lang/lisp/
- lang#livescript:      not loaded          https://spacevim.org/layers/lang/livescript/
- lang#lua:             not loaded          https://spacevim.org/layers/lang/lua/
- lang#markdown:        not loaded          https://spacevim.org/layers/lang/markdown/
- lang#matlab:          not loaded          https://spacevim.org/layers/lang/matlab/
- lang#moonscript:      not loaded          https://spacevim.org/layers/lang/moonscript/
- lang#nim:             not loaded          https://spacevim.org/layers/lang/nim/
- lang#nix:             not loaded          https://spacevim.org/layers/lang/nix/
- lang#ocaml:           not loaded          https://spacevim.org/layers/lang/ocaml/
- lang#pact:            not loaded          https://spacevim.org/layers/lang/pact/
- lang#pascal:          not loaded          https://spacevim.org/layers/lang/pascal/
- lang#perl:            not loaded          https://spacevim.org/layers/lang/perl/
- lang#php:             not loaded          https://spacevim.org/layers/lang/php/
- lang#plantuml:        not loaded          https://spacevim.org/layers/lang/plantuml/
- lang#pony:            not loaded          https://spacevim.org/layers/lang/pony/
- lang#powershell:      not loaded          https://spacevim.org/layers/lang/powershell/
- lang#processing:      not loaded          https://spacevim.org/layers/lang/processing/
- lang#prolog:          not loaded          https://spacevim.org/layers/lang/prolog/
- lang#puppet:          not loaded          https://spacevim.org/layers/lang/puppet/
- lang#purescript:      not loaded          https://spacevim.org/layers/lang/purescript/
- lang#python:          not loaded          https://spacevim.org/layers/lang/python/
- lang#r:               not loaded          https://spacevim.org/layers/lang/r/
- lang#racket:          not loaded          https://spacevim.org/layers/lang/racket/
- lang#red:             not loaded          https://spacevim.org/layers/lang/red/
- lang#ring:            not loaded          https://spacevim.org/layers/lang/ring/
- lang#ruby:            not loaded          https://spacevim.org/layers/lang/ruby/
- lang#rust:            not loaded          https://spacevim.org/layers/lang/rust/
- lang#scala:           not loaded          https://spacevim.org/layers/lang/scala/
- lang#scheme:          not loaded          https://spacevim.org/layers/lang/scheme/
- lang#sh:              not loaded          https://spacevim.org/layers/lang/sh/
- lang#slim:            not loaded          https://spacevim.org/layers/lang/slim/
- lang#solidity:        not loaded          no exists
- lang#sql:             not loaded          no exists
- lang#supercollider:   not loaded          no exists
- lang#swift:           not loaded          https://spacevim.org/layers/lang/swift/
- lang#swig:            not loaded          no exists
- lang#tcl:             not loaded          https://spacevim.org/layers/lang/tcl/
- lang#toml:            not loaded          https://spacevim.org/layers/lang/toml/
- lang#typescript:      not loaded          https://spacevim.org/layers/lang/typescript/
- lang#v:               not loaded          https://spacevim.org/layers/lang/v/
- lang#vbnet:           not loaded          https://spacevim.org/layers/lang/vbnet/
- lang#vim:             not loaded          https://spacevim.org/layers/lang/vim/
- lang#vue:             not loaded          https://spacevim.org/layers/lang/vue/
- lang#wdl:             not loaded          no exists
- lang#wolfram:         not loaded          https://spacevim.org/layers/lang/wolfram/
- lang#xml:             not loaded          https://spacevim.org/layers/lang/xml/
- lang#xquery:          not loaded          no exists
- lang#zig:             not loaded          https://spacevim.org/layers/lang/zig/
- leaderf:              not loaded          https://spacevim.org/layers/leaderf/
- lsp:                  not loaded          https://spacevim.org/layers/language-server-protocol/
- mail:                 not loaded          no exists
- operator:             not loaded          no exists
- org:                  not loaded          no exists
+ shell:                    loaded          https://spacevim.org/layers/shell/
- sudo:                 not loaded          https://spacevim.org/layers/sudo/
- test:                 not loaded          https://spacevim.org/layers/test/
- tmux:                 not loaded          https://spacevim.org/layers/tmux/
- tools#dash:           not loaded          https://spacevim.org/layers/tools/dash/
- tools#mpv:            not loaded          https://spacevim.org/layers/tools/mpv/
- tools#screensaver:    not loaded          no exists
- tools#zeal:           not loaded          https://spacevim.org/layers/tools/zeal/
- tools:                not loaded          https://spacevim.org/layers/tools/
+ ui:                       loaded          https://spacevim.org/layers/ui/
- unite:                not loaded          https://spacevim.org/layers/unite/
- vim:                  not loaded          no exists

Please press <kbd>SPC h I</kbd>, debug info will be put into clipboard, then paste all content below.

## Screenshots

If you have any screenshots for this issue, please upload here. BTW you can use https://asciinema.org/ for recording video in terminal.

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