[Baertram]

I said: The table is missing, not the init of whatever.

This is where "GuildBankLedger.LibHistoireListener" is mentioned the 1st time:

function GuildBankLedger:SetupListener(guildID)
...
  GuildBankLedger.LibHistoireListener[guildID] = LGH:CreateGuildHistoryListener(guildID, GUILD_HISTORY_BANK)

It is using the table "GuildBankLedger.LibHistoireListener" with the index "[guildID]".
But where is the table "GuildBankLedger.LibHistoireListener" defined?

At least not in the file which was attached (searched for GuildBankLedger.LibHistoireListener and self.LibHistoireListener and LibHistoireListener, and there is not any line with = {} or = function which would create that table).

So either add the table init line at the beginning of the file or inside the function itsself like this:

function GuildBankLedger:SetupListener(guildID)
--LGH:RegisterCallback(LibHistoire.callback.INITIALIZED, function()
  -- listener
  d("Starting SetupListenerFunction " .. guildID)
 
  --This was missing: Create the table GuildBankLedger.LibHistoireListener ( = {}) or re-use it if it already exists
  GuildBankLedger.LibHistoireListener = GuildBankLedger.LibHistoireListener or {}
  GuildBankLedger.LibHistoireListener[guildID] = LGH:CreateGuildHistoryListener(guildID, GUILD_HISTORY_BANK)