How do you fix local scripts that need to return tools?

Hello, I need help with a local script of mine. It is in a tool called Mjolnir, but for some reason the script is not working. When I click E it is supposed to make Mjolnir return to me. In the output it says there is an issue.

Here is what the output says:

15:30:19.545 - Infinite yield possible on 'Workspace:WaitForChild("Mjolnir")'

And it also says

15:30:20.517 - Something unexpectedly tried to set the parent of Mjolnir to NULL while trying to set the parent of Mjolnir. Current parent is turbomegapower12345.

and now here is my script

local Humanoid = game.Players.LocalPlayer.Character.Humanoid
local Mjolnir = game.Players.LocalPlayer.Backpack:WaitForChild("Mjolnir")
local name = game.Players.LocalPlayer.Name
local tool = script.Parent
local toolreturn = game.Workspace:WaitForChild("Mjolnir")




--Buffs--

tool.Equipped:connect(function()
	if name ==("turbomegapower1234") then
		Humanoid.MaxHealth = 100000
		Humanoid.Health = 100000
		Humanoid.WalkSpeed = 100
	else
		Mjolnir:Remove()
		
	end    
end)

--Removing Buffs --

tool.Unequipped:connect(function()
	if name ==("turbomegapower12345") then
		Humanoid.MaxHealth = 100
		Humanoid.Health = 100
		Humanoid.WalkSpeed = 16
	end
end)

--this section is the one I need help on!--

local player = game.Players.LocalPlayer
local character = player.Character

local mouse = player:GetMouse()
mouse.KeyDown:connect(function(key)
    if key == "e" then
	character.Humanoid:EquipTool(toolreturn)
else

    end
end)

Thank you for the help!

This is because you are using deprecated code and wrapping strings in brackets.

local plr = game:GetService("Players").LocalPlayer
local mjolnir = plr.Backpack:WaitForChild"Mjolnir"
local tool = script.Parent
local toolReturn = game.Workspace.Mjolnir

tool.Equipped:Connect(function(mouse) --Connect not :connect 
    if plr.Name == 'turbomegapower12345' then -- no brackets
        plr.Character.Humanoid.WalkSpeed = 16
        plr.Character.Humanoid.MaxHealth = 100000
        plr.Character.Humanoid.Health = 100000
    else
        mjolnir:Destroy() -- Destroy not Remove
    end
end)

tool.Unequipped:Connect(function()
    if plr.Name == 'turbomegapower12345' then
        plr.Character.Humanoid.WalkSpeed = 16
        plr.Character.Humanoid.MaxHealth = 100
        plr.Character.Humanoid.Health = 100
    end
end)

function equipTool() --keydown is deprecated, make a function to bind with CAS 
    plr.Character.Humanoid:EquipTool(toolReturn)
end

game:GetService('ContextActionService'):BindAction('EquipTool', --use this
    equipTool, 
    false,
    Enum.KeyCode.E --you can set a variety of keys not only one key 
)