Attempt to index boolean with 'waitforchild' error

So I'm trying to make a LocalScript that connects to a ServerScript through a remote event which makes a Gui appear. The error is that every time I fire the remote event I need it to happen for one player only so I use :FireClient in the ServerScript but I get an error from the LocalScript saying "attempt to index boolean with 'waitforchild' and I don't know how to fix the error on my own

The error happens on Line 7

Here is my code

local player = game:GetService("Players").LocalPlayer
local ToggleTPMenuEvent = game.ReplicatedStorage.TeleportEvents.ToggleTPMenu

local TPMenu = player.PlayerGui.TeleportMenu.Frame

ToggleTPMenuEvent.OnClientEvent:Connect(function(Player:Player)
    Player.PlayerGui:WaitForChild("TeleportMenu"):WaitForChild("Frame").Visible = true
    Player.PlayerGui:WaitForChild("TeleportMenu"):WaitForChild("Frame"):WaitForChild("TextLabel").Visible = true
    Player.PlayerGui:WaitForChild("TeleportMenu"):WaitForChild("Frame"):WaitForChild("PlayButton").Visible = true
    Player.PlayerGui:WaitForChild("TeleportMenu"):WaitForChild("Frame"):WaitForChild("ChaptersFrame").Visible = true
    
end)

Solution

When you fire a RemoteEvent from the server, the Player argument does not get passed to the client.

If the server calls...

remoteEvent:FireClient(player1, a, b, c)

The client will receive...

remoteEvent.OnClientEvent:Connect(function(a, b, c)

In your code, your client event handler is trying to handle the Player argument, but actually the value being assigned to the Player argument is a Boolean.

Since this is a LocalScript, use the Players.LocalPlayer to get the gui. You're already doing this, so just use the TPMenu variable. Then, use the boolean from the server script to toggle the visibility :

local player = game:GetService("Players").LocalPlayer
local ToggleTPMenuEvent = game.ReplicatedStorage.TeleportEvents.ToggleTPMenu

ToggleTPMenuEvent.OnClientEvent:Connect(function(isVisible)
    local TPMenu = player.PlayerGui.TeleportMenu.Frame

    TPMenu.Visible = isVisible
    TPMenu.TextLabel.Visible = isVisible
    TPMenu.PlayButton.Visible = isVisible
    TPMenu.ChaptersFrame.Visible = isVisible
end)