E704 when opening nerdtree or new directory

[Coleej]

With the newest commit, when I toggle Nerdtree or navigate to a new directory, Vim throws this error:

E704: Funcref variable name must start with a capital: l:numChildrenCached

The directory is not populated with any other nodes. I reverted back to commit: '288669db1fa888947deaf715d7469233f476909f' and the problem disappeared.

Environment

• Operating System: Linux, both ubuntu 18.04 (4.18 kernel) and Arch (5.0.4 kernel)

• Vim version :version:

Included patches: 1-547
Compiled by cjohnson@mobile
Huge version with GTK2-GNOME GUI.  Features included (+) or not (-):
+acl               +clientserver      +diff              +folding           +libcall           -mouse_gpm         +packages          -ruby              +termguicolors     +visual            +xsmp_interact
+arabic            +clipboard         +digraphs          -footer            +linebreak         -mouse_jsbterm     +path_extra        +scrollbind        +terminal          +visualextra       +xterm_clipboard
+autocmd           +cmdline_compl     +dnd               +fork()            +lispindent        +mouse_netterm     -perl              +signs             +terminfo          +viminfo           -xterm_save
+autochdir         +cmdline_hist      -ebcdic            +gettext           +listcmds          +mouse_sgr         +persistent_undo   +smartindent       +termresponse      +vreplace
+autoservername    +cmdline_info      +emacs_tags        -hangul_input      +localmap          -mouse_sysmouse    +postscript        +startuptime       +textobjects       +wildignore
+balloon_eval      +comments          +eval              +iconv             -lua               +mouse_urxvt       +printer           +statusline        +timers            +wildmenu
+balloon_eval_term +conceal           +ex_extra          +insert_expand     +menu              +mouse_xterm       +profile           -sun_workshop      +title             +windows
+browse            +cryptv            +extra_search      +job               +mksession         +multi_byte        -python            +syntax            +toolbar           +writebackup
++builtin_terms    +cscope            +farsi             +jumplist          +modify_fname      +multi_lang        +python3/dyn       +tag_binary        +user_commands     +X11
+byte_offset       +cursorbind        +file_in_path      +keymap            +mouse             -mzscheme          +quickfix          +tag_old_static    +vartabs           -xfontset
+channel           +cursorshape       +find_in_path      +lambda            +mouseshape        +netbeans_intg     +reltime           -tag_any_white     +vertsplit         +xim
+cindent           +dialog_con_gui    +float             +langmap           +mouse_dec         +num64             +rightleft         -tcl               +virtualedit       +xpm
   system vimrc file: "$VIM/vimrc"
     user vimrc file: "$HOME/.vimrc"
 2nd user vimrc file: "~/.vim/vimrc"
      user exrc file: "$HOME/.exrc"
  system gvimrc file: "$VIM/gvimrc"
    user gvimrc file: "$HOME/.gvimrc"
2nd user gvimrc file: "~/.vim/gvimrc"
       defaults file: "$VIMRUNTIME/defaults.vim"
    system menu file: "$VIMRUNTIME/menu.vim"
  fall-back for $VIM: "/usr/local/stow/vim81-0547/share/vim"
Compilation: gcc -c -I. -Iproto -DHAVE_CONFIG_H -DFEAT_GUI_GTK  -pthread -I/usr/include/gtk-2.0 -I/usr/lib/x86_64-linux-gnu/gtk-2.0/include -I/usr/include/gio-unix-2.0/ -I/usr/include/cairo -I/usr/include/pango-1.
0 -I/usr/include/atk-1.0 -I/usr/include/cairo -I/usr/include/pixman-1 -I/usr/include/gdk-pixbuf-2.0 -I/usr/include/libpng16 -I/usr/include/pango-1.0 -I/usr/include/harfbuzz -I/usr/include/pango-1.0 -I/usr/include/
glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include -I/usr/include/freetype2 -I/usr/include/libpng16 -I/usr/include/freetype2 -I/usr/include/libpng16 -D_REENTRANT -DORBIT2=1 -pthread -I/usr/include/libgnomeui-2.
0 -I/usr/include/gnome-keyring-1 -I/usr/include/libbonoboui-2.0 -I/usr/include/libxml2 -I/usr/include/libgnome-2.0 -I/usr/include/libbonobo-2.0 -I/usr/include/bonobo-activation-2.0 -I/usr/include/orbit-2.0 -I/usr/
include/libgnomecanvas-2.0 -I/usr/include/gail-1.0 -I/usr/include/libart-2.0 -I/usr/include/gtk-2.0 -I/usr/lib/x86_64-linux-gnu/gtk-2.0/include -I/usr/include/gio-unix-2.0/ -I/usr/include/cairo -I/usr/include/pang
o-1.0 -I/usr/include/atk-1.0 -I/usr/include/cairo -I/usr/include/pixman-1 -I/usr/include/pango-1.0 -I/usr/include/harfbuzz -I/usr/include/pango-1.0 -I/usr/include/freetype2 -I/usr/include/libpng16 -I/usr/include/f
reetype2 -I/usr/include/libpng16 -I/usr/include/gdk-pixbuf-2.0 -I/usr/include/libpng16 -I/usr/include/gnome-vfs-2.0 -I/usr/lib/x86_64-linux-gnu/gnome-vfs-2.0/include -I/usr/include/gconf/2 -I/usr/include/dbus-1.0
-I/usr/lib/x86_64-linux-gnu/dbus-1.0/include -I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include   -O3 -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=1
Linking: gcc   -L/usr/local/lib -Wl,--as-needed -o vim   -lgtk-x11-2.0 -lgdk-x11-2.0 -lpangocairo-1.0 -latk-1.0 -lcairo -lgdk_pixbuf-2.0 -lgio-2.0 -lpangoft2-1.0 -lpango-1.0 -lgobject-2.0 -lglib-2.0 -lfontconfig -
lfreetype  -lgnomeui-2 -lSM -lICE -lbonoboui-2 -lgnome-2 -lpopt -lbonobo-2 -lbonobo-activation -lORBit-2 -lgnomecanvas-2 -lart_lgpl_2 -lgtk-x11-2.0 -lgdk-x11-2.0 -lpangocairo-1.0 -latk-1.0 -lcairo -lgio-2.0 -lpang
oft2-1.0 -lpango-1.0 -lfontconfig -lfreetype -lgdk_pixbuf-2.0 -lgnomevfs-2 -lgconf-2 -lgthread-2.0 -lgmodule-2.0 -lgobject-2.0 -lglib-2.0 -lSM -lICE -lXpm -lXt -lX11 -lXdmcp -lSM -lICE  -lm -ltinfo -lnsl  -lselinu
x  -ldl```

* NERDTree version `git rev-parse --short HEAD`: 0efbdfb

* NERDTree settings applied in your vimrc, if any:
```" << NERDTree >> {{{

let g:NERDTreeWinSize = 52
au bufenter * if (winnr("$") == 1 && exists("b:NERDTree") && b:NERDTree.isTabTree()) | q | endif
" function to open NERDTree depending on filetype
"au vimenter * call s:CheckToOpenNERDTree()

function! s:CheckToOpenNERDTree() abort

	" Open for python
	if &filetype == 'python'
		NERDTree
	endif

	" Open for c
	if &filetype == 'c'
		NERDTree
	endif

endfunction

" user NERDTree when opening directory
autocmd StdinReadPre * let s:std_in=1
autocmd VimEnter * if argc() == 1 && isdirectory(argv()[0]) && !exists("s:std_in") | exe 'NERDTree' argv()[0] | wincmd p | ene | endif

" }}}```


### Process
<!--- List the steps that will recreate the issue. -->

1. open nerdtree or navigate to new directory

### Current Result
error is thrown and no nodes are loaded into the tree

### Expected Result
navigate directory tree

### Screenshot(s)

### Possible Fix
revert to commit '288669db1fa888947deaf715d7469233f476909f'

[terryding77]

I meet the same problem and simply add a pair of brackets to _initChildren func, I resolve it.

[robinchm]

Also encountered the exactly same issue and reverting to previous commit "288669d" indeed works.

[PhilRunninger]

Fixed by PR #969. Thanks, @terryding77 .