Creating aura errors '/fstack' command

[Layback_]

Before I start, if I am violating any rules of this forum, please let me know!
( Why is there no delete button on forum D: )

Anyways...

I was creating a auras frame and just copy-pasted the example code provided inside aura.lua file to see how it looks like.

A.CreateBuffs = function(f, unit)
    local Buffs = CreateFrame("Frame", "$parentBuffs", f);
    Buffs:SetPoint("RIGHT", f, "LEFT");
    Buffs:SetSize(16 * 2, 16 * 16);
 
    f.Buffs = Buffs;
end

After that, I used '/fstack' command which passed me the following error.

Message: invalid key to 'next'
Time: 07/28/16 19:29:53
Count: 1
Stack: [C]: in function `SetFrameStack'
...e\AddOns\Blizzard_DebugTools\Blizzard_DebugTools.lua:715: in function `FrameStackTooltip_Toggle'
Interface\FrameXML\ChatFrame.lua:2293: in function `?'
Interface\FrameXML\ChatFrame.lua:4332: in function `ChatEdit_ParseText'
Interface\FrameXML\ChatFrame.lua:4000: in function `ChatEdit_SendText'
Interface\FrameXML\ChatFrame.lua:2631: in function <Interface\FrameXML\ChatFrame.lua:2624>
[C]: in function `UseAction'
Interface\FrameXML\SecureTemplates.lua:348: in function `handler'
Interface\FrameXML\SecureTemplates.lua:621: in function `SecureActionButton_OnClick'
Interface\FrameXML\MultiActionBars.lua:24: in function `MultiActionButtonUp'
[string "MULTIACTIONBAR3BUTTON5"]:4: in function <[string "MULTIACTIONBAR3BUTTON5"]:1>

I honestly can't even think of what is causing this error ...

Does anyone know what is going wrong with this?