Fix a crash when pressing F10 on a window that has no main menu
Fix a crash when pressing F10 on a window that has no main menu

AvaloniaUI/Avalonia,AvaloniaUI/Avalonia,grokys/Perspex,jkoritzinsky/Avalonia,wieslawsoltes/Perspex,SuperJMN/Avalonia,AvaloniaUI/Avalonia,SuperJMN/Avalonia,akrisiun/Perspex,SuperJMN/Avalonia,jkoritzinsky/Perspex,wieslawsoltes/Perspex,wieslawsoltes/Perspex,SuperJMN/Avalonia,AvaloniaUI/Avalonia,SuperJMN/Avalonia,jkoritzinsky/Avalonia,wieslawsoltes/Perspex,wieslawsoltes/Perspex,AvaloniaUI/Avalonia,AvaloniaUI/Avalonia,SuperJMN/Avalonia,Perspex/Perspex,wieslawsoltes/Perspex,jkoritzinsky/Avalonia,grokys/Perspex,wieslawsoltes/Perspex,jkoritzinsky/Avalonia,Perspex/Perspex,jkoritzinsky/Avalonia,jkoritzinsky/Avalonia,jkoritzinsky/Avalonia,AvaloniaUI/Avalonia,SuperJMN/Avalonia