How can i fix "ServerScriptService.Tycoon:74: attempt to index nil with 'Event'"?

How can i fix that? i swear to god i'm losing my mind (The error is in the line 74)

local CollectionService = game:GetService("CollectionService")
local template = game:GetService("ServerStorage").Template
local componentFolder = script.Parent.Components
local tycoonStorage = game:GetService("ServerStorage").TycoonStorage

local function NewModel(model, cframe)
	local newModel = model:Clone()
	newModel:PivotTo(cframe)
	newModel.Parent = workspace
	return newModel
end

local Tycoon = {}
Tycoon.__index = Tycoon

function Tycoon.new(player)
	local self = setmetatable({}, Tycoon)
	self.Owner = player

	self._topicEvent = Instance.new("BindableEvent")	
	return self
end

function Tycoon:Init()
	self.Model = NewModel(template, CFrame.new(0, 1, 0))

	self:LockAll()

	wait(7)
	self:PublishTopic("Button", "BasicPart")
end

function Tycoon:LockAll()
	for _, instance in ipairs(self.Model:GetDescendants()) do
		if CollectionService:HasTag(instance, "Unlockable") then
			self:Lock(instance)
		else
			self:AddComponents(instance)
		end
	end
end

function Tycoon:Lock(instance)
	instance.Parent = tycoonStorage
	self:CreateComponent(instance, componentFolder.Unlockable)
end

function Tycoon:Unlock(instance, id)
	CollectionService:RemoveTag(instance, "Unlockable")
	self:AddComponents(instance)
	instance.Parent = self.Model
end

function Tycoon:AddComponents(instance)
	for _, tag in ipairs(CollectionService:GetTags(instance)) do
		local component = componentFolder:FindFirstChild(tag)
		if component then 
			self:CreateComponent(instance, component)
		end
	end
end

function Tycoon:CreateComponent(instance, componentScript)
	local compModule = require(componentScript)
	local newComp = compModule.new(self, instance)
	newComp:Init()
end

function Tycoon:PublishTopic(topicName, ...)
	self._topicEvent:Fire(topicName, ...)
end

function Tycoon:SubscribeTopic(topicName, callback)
	local connection = self._topicEvent.Event:Connect(function(name, ...)
		if name == topicName then
			callback(...)
		end
	end)
	return connection
end

function Tycoon:Destroy()
	self.Model:Destroy()
	self._topicEvent:Destroy()
end

return Tycoon

Okay, this question took me a minute but I believe I have solved your issue.

The issue comes in Tycoon.new(player).

Instead of defining a variable that has a metatable as its value, you could (and should) just return the metatable with all the necessary variables defined within the table:

function Tycoon.new(player)
	return setmetatable({
		Owner = player;
		_topicEvent = Instance.new("BindableEvent");
	}, Tycoon)
end

I hope this makes sense. If it doesn't, feel free to reach out to me here