Duplicate entry '' for key 'callsign'

[ThatMadCap]

[       script:ps_lib] SCRIPT ERROR: citizen:/scripting/lua/scheduler.lua:750: SCRIPT ERROR: @ps-mdt-v3/server/functions.lua:145: ps-mdt-v3 was unable to execute a query!
[       script:ps_lib] Query: INSERT INTO mdt_profiles (citizenid, fullname, callsign, notes, profilepicture) VALUES (?,?,?,?,?)
[       script:ps_lib] ["CKO24284","Laura Spikes","","",""]
[       script:ps_lib] Duplicate entry '' for key 'callsign'

I think this derives from:
https://github.com/Project-Sloth/ps-mdt-v3/blob/30540940ee4ea557c5a339ed28e0616102acef65/server/functions.lua#L131-L148

ps.registerCallback('ps-mdt:hasProfile', function(source)
    local src = source
    assert(src, 'Player ID cannot be nil')
    local citizenId = ps.getIdentifier(src)
    if not citizenId then
        ps.warn('No citizen ID found for source: ' .. tostring(src))
        return false
    end


    -- Check if the player has a profile in the MDT
    local hasProfile = MySQL.scalar.await('SELECT COUNT(*) FROM mdt_profiles WHERE citizenid = ?', { citizenId })
    if hasProfile and hasProfile > 0 then
        return true
    else
        MySQL.insert.await('INSERT INTO mdt_profiles (citizenid, fullname, callsign, notes, profilepicture) VALUES (?,?,?,?,?)', 
        { citizenId, ps.getPlayerName(source), "", "", "" })
    end
end)

This occurred when logging out and making a new character (already having another one). It happens every time you load that new character. The MDT profile for that new character does look like it was created though.