PlugClean crash with PowerShell

Explain the problem here ...

Here is my minimal _vimrc with shell is PowerShell
```
"General settings
syntax on
set nocompatible
set background=dark
set noswapfile
set linespace=8
set textwidth=120
set shell=C:\Windows\System32\WindowsPowerShell\v1.0\powershell.exe

```
When I use :PlugClean it crash and return

but delete `set shell=C:\Windows\System32\WindowsPowerShell\v1.0\powershell.exe` it's ok.

------------------------------

Vim version:
```
VIM - Vi IMproved 8.2 (2019 Dec 12, compiled Aug 26 2021 22:02:38)
MS-Windows 64-bit GUI version with OLE support
Included patches: 1-3377
Compiled by appveyor@APPVYR-WIN
Huge version with GUI. Features included (+) or not (-):
+acl +cmdline_compl -ebcdic +insert_expand +mksession +popupwin +sound +textprop +wildignore
+arabic +cmdline_hist +emacs_tags +ipv6 +modify_fname -postscript +spell -tgetent +wildmenu
+autocmd +cmdline_info +eval +job +mouse +printer +startuptime +timers +windows
+autochdir +comments +ex_extra +jumplist +mouseshape +profile +statusline +title +writebackup
+autoservername +conceal +extra_search +keymap +multi_byte_ime/dyn +python/dyn -sun_workshop +toolbar -xfontset
+balloon_eval +cryptv -farsi +lambda +multi_lang +python3/dyn +syntax +user_commands -xim
-balloon_eval_term +cscope +file_in_path +langmap +mzscheme/dyn +quickfix +tag_binary +vartabs +xpm_w32
+browse +cursorbind +find_in_path +libcall +netbeans_intg +reltime -tag_old_static +vertsplit -xterm_save
++builtin_terms +cursorshape +float +linebreak +num64 +rightleft -tag_any_white +virtualedit
+byte_offset +dialog_con_gui +folding +lispindent +ole +ruby/dyn +tcl/dyn +visual
+channel +diff -footer +listcmds +packages +scrollbind -termguicolors +visualextra
+cindent +digraphs +gettext/dyn +localmap +path_extra +signs +terminal +viminfo
+clientserver +directx -hangul_input +lua/dyn +perl/dyn +smartindent -termresponse +vreplace
+clipboard -dnd +iconv/dyn +menu +persistent_undo -sodium +textobjects -vtp
system vimrc file: "$VIM\vimrc"
user vimrc file: "$HOME\_vimrc"
2nd user vimrc file: "$HOME\vimfiles\vimrc"
3rd user vimrc file: "$VIM\_vimrc"
user exrc file: "$HOME\_exrc"
2nd user exrc file: "$VIM\_exrc"
system gvimrc file: "$VIM\gvimrc"
user gvimrc file: "$HOME\_gvimrc"
2nd user gvimrc file: "$HOME\vimfiles\gvimrc"
3rd user gvimrc file: "$VIM\_gvimrc"
defaults file: "$VIMRUNTIME\defaults.vim"
system menu file: "$VIMRUNTIME\menu.vim"
Compilation: cl -c /W3 /GF /nologo -I. -Iproto -DHAVE_PATHDEF -DWIN32 -DFEAT_CSCOPE -DFEAT_TERMINAL -DFEAT_SOUND -DFEAT_NETBEANS_INTG -DFEAT_JOB_CHANNEL -DFEAT_IPV6 -DFEAT_XPM_W32 -DWINVER=0x0501 -D_WIN32_WINNT=0x0501 /source-charset:utf-8 /MP -DHAVE_STDINT_H /Ox /GL -DNDEBUG /Zl /MT /D_CRT_SECURE_NO_DEPRECATE /D_CRT_NONSTDC_NO_DEPRECATE -DFEAT_OLE -DFEAT_MBYTE_IME -DDYNAMIC_IME -DFEAT_GUI_MSWIN -DFEAT_DIRECTX -DDYNAMIC_DIRECTX -DFEAT_DIRECTX_COLOR_EMOJI -DDYNAMIC_ICONV -DDYNAMIC_GETTEXT -DFEAT_TCL -DDYNAMIC_TCL -DDYNAMIC_TCL_DLL=\"tcl86t.dll\" -DDYNAMIC_TCL_VER=\"8.6\" -DFEAT_LUA -DDYNAMIC_LUA -DDYNAMIC_LUA_DLL=\"lua53.dll\" -DFEAT_PYTHON -DDYNAMIC_PYTHON -DDYNAMIC_PYTHON_DLL=\"python27.dll\" -DFEAT_PYTHON3 -DDYNAMIC_PYTHON3 -DDYNAMIC_PYTHON3_DLL=\"python39.dll\" -DFEAT_MZSCHEME -I "C:\Program Files\Racket\include" -DMZ_PRECISE_GC -DDYNAMIC_MZSCHEME -DDYNAMIC_MZSCH_DLL=\"libracket3m_a36fs8.dll\" -DDYNAMIC_MZGC_DLL=\"libracket3m_a36fs8.dll\" -DFEAT_PERL -DPERL_IMPLICIT_CONTEXT -DPERL_IMPLICIT_SYS -DDYNAMIC_PERL -DDYNAMIC_PERL_DLL=\"perl528.dll\" -DFEAT_RUBY -DDYNAMIC_RUBY -DDYNAMIC_RUBY_DLL=\"x64-msvcrt-ruby240.dll\" -DRUBY_VERSION=24 -DFEAT_HUGE /Fd.\ObjGXOULYHTRZAMD64/ /Zi
Linking: link /nologo /opt:ref /LTCG:STATUS /HIGHENTROPYVA:NO oldnames.lib kernel32.lib advapi32.lib shell32.lib gdi32.lib comdlg32.lib ole32.lib netapi32.lib uuid.lib /machine:AMD64 gdi32.lib version.lib winspool.lib comctl32.lib advapi32.lib shell32.lib netapi32.lib /machine:AMD64 libcmt.lib oleaut32.lib user32.lib /nodefaultlib:lua53.lib /STACK:8388608 /nodefaultlib:python27.lib /nodefaultlib:python39.lib "C:\Tcl\lib\tclstub86.lib" winmm.lib WSock32.lib Ws2_32.lib xpm\x64\lib-vc14\libXpm.lib /PDB:gvim.pdb -debug

```

- Type:
- [X] Bug
- OS:
- [X] Windows
- Vim:
- [X] GVim