fix(monitor): 🐛 add check for undefined hyprlandMonitor to avoid MonitorRefresh crash

[KernelDiego]

Crashes when trying to take a screenshot of a monitor that is undefined.

(gjs:108409): hyprpanel-CRITICAL **: 19:47:48.757: [MonitorRefresh] Error during component refresh: TypeError: hyprlandMonitor is undefined
_matchMonitorKey@file:///usr/share/hyprpanel/hyprpanel.js:16645:9
mapHyprlandToGdk/<@file:///usr/share/hyprpanel/hyprpanel.js:16594:44
_matchMonitor/directMatch<@file:///usr/share/hyprpanel/hyprpanel.js:16614:30
_matchMonitor@file:///usr/share/hyprpanel/hyprpanel.js:16613:36
mapHyprlandToGdk@file:///usr/share/hyprpanel/hyprpanel.js:16589:17
notifications_default5/windowMonitor<@file:///usr/share/hyprpanel/hyprpanel.js:24076:46
update@file:///usr/share/hyprpanel/hyprpanel.js:306:32
derive@file:///usr/share/hyprpanel/hyprpanel.js:307:38
notifications_default5@file:///usr/share/hyprpanel/hyprpanel.js:24072:34
_refreshMonitors@file:///usr/share/hyprpanel/hyprpanel.js:29819:7
async*handleMonitorChange/this._monitorChangeTimeout<@file:///usr/share/hyprpanel/hyprpanel.js:29796:12
setTimeout/source<@resource:///org/gnome/gjs/modules/esm/_timers.js:72:9
_init/GLib.MainLoop.prototype.runAsync/</<@resource:///org/gnome/gjs/modules/core/overrides/GLib.js:263:34