Command problem with "context" null | latcord | Page 1

Hey i got a problem they says that "context is not define but i don't understand why i should define context when normally i don't have to on other commands

let createui = (event, player, page) => {
    player.openChestGUI(Text.of(Text.white('test')), 6, gui => {
        gui.playerSlots = false
        gui.slot(1, 2, slot => {
            slot.item = 'minecraft:diamond'
            slot.leftClicked = e => {
                event.player.sendSystemMessage('§ayummers')
            }
        })
        gui.slot(7, 1, slot => {
            slot.item = 'minecraft:dead_bush'
            slot.leftClicked = e => {
                event.player.sendSystemMessage('§4yuckers')
            }
        })
    })
}



ServerEvents.commandRegistry(event => {
    const { commands: Commands } = event;

    event.register(
        Commands.literal("menu")
        .executes(context => {
            const source = context.getSource();
            const player = source.player
            createui(event, event.player, 0) 
            return 1;
        })
    );
});```

#Command problem with "context" null