[EscherechiaColi]

Sorry... I thought it would be better that way. So here we go:

-- First, we create a namespace for our addon by declaring a top-level table that will hold everything else.
RemiCustomAddon = {}
 
-- This isn't strictly necessary, but we'll use this string later when registering events.
-- Better to define it in a single place rather than retyping the same string.
RemiCustomAddon.name = "RemiCustomAddon"
 
function RemiCustomAddon:RestorePositionBagSpace()
    local leftBagSpace = self.savedVariables.leftBagSpace
    local topBagSpace = self.savedVariables.topBagSpace
   
    RemiCustomAddonIndicator:ClearAnchors()
    RemiCustomAddonIndicator:SetAnchor(TOPLEFT, GuiRoot, TOPLEFT, leftBagSpace, topBagSpace)
end
 
function RemiCustomAddon:RestorePositionFight()
    local leftFight = self.savedVariables.leftFight
    local topFight = self.savedVariables.topFight
   
    FightIndicator:ClearAnchors()
    FightIndicator:SetAnchor(TOPLEFT, GuiRoot, TOPLEFT, leftFight, topFight)
end
 
-- Next we create a function that will initialize our addon
function RemiCustomAddon:Initialize()
    self.inCombat = IsUnitInCombat("player");
    
 
    EVENT_MANAGER:RegisterForEvent(self.name, EVENT_PLAYER_COMBAT_STATE, self.OnPlayerCombatState)
    EVENT_MANAGER:RegisterForEvent(self.name, EVENT_GROUPING_TOOLS_READY_CHECK_UPDATED, self.OnLFGReadyCheckState)
    EVENT_MANAGER:RegisterForEvent(self.name, EVENT_PLAYER_ACTIVATED, self.DoesBagHaveSpace)
 
    self.savedVariables = ZO_SavedVars:New("RemiCustomAddonSavedVariables", 1, nil, {})
    self:RestorePositionBagSpace()
    self:RestorePositionFight()
end
 
function RemiCustomAddon.DoesBagHaveSpace(eventCode, initial)
    itemSpace = GetNumBagFreeSlots(1)
    if itemSpace < 10 then
        RemiCustomAddonIndicator:SetHidden(false)
   end
end
 
function RemiCustomAddon.OnLFGReadyCheckState(event)
    if HasLFGReadyCheckNotification() then
        AcceptLFGReadyCheckNotification()
    end
end
 
function RemiCustomAddon.OnPlayerCombatState(event, inCombat)
    -- The ~= operator is "not equal to" in Lua.
    if inCombat ~= RemiCustomAddon.inCombat then
      -- The player's state has changed. Update the stored state...
      RemiCustomAddon.inCombat = inCombat
   
      -- ...and then update the control.
      FightIndicator:SetHidden(not inCombat)
    end
end
 
function RemiCustomAddon.OnIndicatorMoveStopFight()
    RemiCustomAddon.savedVariables.leftFight = FightIndicator:GetLeft()
    RemiCustomAddon.savedVariables.topFight = FightIndicator:GetTop()
end
 
function RemiCustomAddon.OnIndicatorMoveStopBagSpace()
    RemiCustomAddon.savedVariables.leftBagSpace = RemiCustomAddonIndicator:GetLeft()
    RemiCustomAddon.savedVariables.topBagSpace = RemiCustomAddonIndicator:GetTop()
end
 
-- Then we create an event handler function which will be called when the "addon loaded" event
-- occurs. We'll use this to initialize our addon after all of its resources are fully loaded.
function RemiCustomAddon.OnAddOnLoaded(event, addonName)
  -- The event fires each time *any* addon loads - but we only care about when our own addon loads.
  if addonName == RemiCustomAddon.name then
    RemiCustomAddon:Initialize()
  end
end
 
-- Finally, we'll register our event handler function to be called when the proper event occurs.
EVENT_MANAGER:RegisterForEvent(RemiCustomAddon.name, EVENT_ADD_ON_LOADED, RemiCustomAddon.OnAddOnLoaded)

As for the error messages, here it is (expanded):

user:/AddOns/RemiCustomAddon/RemiCustomAddon.lua:12: attempt to index a nil value
stack traceback:
user:/AddOns/RemiCustomAddon/RemiCustomAddon.lua:12: in function 'RemiCustomAddon:RestorePositionBagSpace'
|caaaaaa<Locals> self = [table:1]{inCombat = F, name = "RemiCustomAddon"} </Locals>|r
user:/AddOns/RemiCustomAddon/RemiCustomAddon.lua:34: in function 'RemiCustomAddon:Initialize'
|caaaaaa<Locals> self = [table:1] </Locals>|r
user:/AddOns/RemiCustomAddon/RemiCustomAddon.lua:77: in function 'RemiCustomAddon.OnAddOnLoaded'
|caaaaaa<Locals> event = 65536, addonName = "RemiCustomAddon" </Locals>|r

But to be honest, I don't really see what to do with this information myself... I don't quite understand what would be missing.

For LibDebugLogger, sorry it took quite a lot of time for me to understand how to use it...
Here is the file:
https://sir.insidi.at/or/logviewer/NVxFbP

As for the .txt file, yes I tried putting .xml files before and after the .lua file, no change. I also already tried removing the OnInitialization code (commenting it with --) to no avail.