Button is null

[ghost]

Describe the bug
May be the same issue with #313, but on version 72.

Environment (please complete the following information):

• OS: Arch Linux
• GNOME Shell 44.5
• Unite 72

Logs
JS ERROR: Extension unite@hardpixel.eu: TypeError: buttons is null
_onLayoutChange@/home/user/.local/share/gnome-shell/extensions/unite@hardpixel.eu/panel.js:125:7
_onPositionChange@/home/user/.local/share/gnome-shell/extensions/unite@hardpixel.eu/panel.js:149:10
activate@/home/user/.local/share/gnome-shell/extensions/unite@hardpixel.eu/panel.js:72:10
onChange@/home/user/.local/share/gnome-shell/extensions/unite@hardpixel.eu/handlers.js:242:24
add/feature._doActivate@/home/user/.local/share/gnome-shell/extensions/unite@hardpixel.eu/handlers.js:253:7
activate/<@/home/user/.local/share/gnome-shell/extensions/unite@hardpixel.eu/handlers.js:265:46
activate@/home/user/.local/share/gnome-shell/extensions/unite@hardpixel.eu/handlers.js:265:19
activate@/home/user/.local/share/gnome-shell/extensions/unite@hardpixel.eu/panel.js:681:21
activate@/home/user/.local/share/gnome-shell/extensions/unite@hardpixel.eu/extension.js:24:25
enable@/home/user/.local/share/gnome-shell/extensions/unite@hardpixel.eu/extension.js:45:16
_callExtensionEnable@resource:///org/gnome/shell/ui/extensionSystem.js:196:38
loadExtension@resource:///org/gnome/shell/ui/extensionSystem.js:398:32
async*_loadExtensions@resource:///org/gnome/shell/ui/extensionSystem.js:677:24
async*_enableAllExtensions@resource:///org/gnome/shell/ui/extensionSystem.js:683:48
_sessionUpdated@resource:///org/gnome/shell/ui/extensionSystem.js:718:20
async*init@resource:///org/gnome/shell/ui/extensionSystem.js:59:14
_initializeUI@resource:///org/gnome/shell/ui/main.js:311:22
start@resource:///org/gnome/shell/ui/main.js:186:5
@resource:///org/gnome/shell/ui/init.js:6:17

[ghost]

i forget i've disabled buttons via gsettings before. This issue is solved by entering command

gsettings set org.gnome.desktop.wm.preferences button-layout 'appmenu:minimize,maximize,close'