Fix Minetest blaming the wrong mod for errors (minetest#12241)

Covers the case where mods insert their callbacks manually into "minetest.registered_<callbacks>" (often to achieve a particular order of execution).

builtin/client/register.lua

@@ -1,4 +1,3 @@
-
 core.callback_origins = {}
 
 local getinfo = debug.getinfo

builtin/game/item.lua

@@ -529,9 +529,7 @@ function core.node_dig(pos, node, digger)
  -- Run script hook
  for _, callback in ipairs(core.registered_on_dignodes) do
  local origin = core.callback_origins[callback]
- if origin then
- core.set_last_run_mod(origin.mod)
- end
+ core.set_last_run_mod(origin.mod)
 
  -- Copy pos and node because callback can modify them
  local pos_copy = vector.new(pos)

builtin/game/register.lua

@@ -403,8 +403,14 @@ function core.override_item(name, redefinition)
  register_item_raw(item)
 end
 
-
-core.callback_origins = {}
+do
+ local default = {mod = "??", name = "??"}
+ core.callback_origins = setmetatable({}, {
+ __index = function()
+ return default
+ end
+ })
+end
 
 function core.run_callbacks(callbacks, mode, ...)
  assert(type(callbacks) == "table")
@@ -419,9 +425,7 @@ function core.run_callbacks(callbacks, mode, ...)
  local ret = nil
  for i = 1, cb_len do
  local origin = core.callback_origins[callbacks[i]]
- if origin then
- core.set_last_run_mod(origin.mod)
- end
+ core.set_last_run_mod(origin.mod)
  local cb_ret = callbacks[i](...)
 
  if mode == 0 and i == 1 then