Merge branch 'nil_check_hudbar_state' of fluxionary for hudbar state checks

* another fix for https://codeberg.org/Wuzzy/minetest_hudbars/issues/4
  based on separate callbacks, when we have several mods that rely on
* this solves and close https://codeberg.org/Wuzzy/minetest_hudbars/issues/4
  but will need https://codeberg.org/Wuzzy/minetest_hudbars/pulls/7 also.
* this must be use in join with commit 20843d95ce
  of this repository that is a backport of my own fork at @mckaygerhard

API.md

@@ -187,7 +187,7 @@ Makes a previously hidden HUD bar visible again to a player.
 It is also possible to read information about existing HUD bars.
 
 ### `hb.get_hudbar_state(player, identifier)`
-Returns the current state of the active player's HUD bar.
+Returns the current state of the active player's HUD bar. Will return `nil` if the hudbar is not initialized.
 
 #### Parameters
 * `player`: `ObjectRef` of the player to which the HUD bar belongs to

init.lua

@@ -485,6 +485,7 @@ end
 function hb.get_hudbar_state(player, identifier)
 	if not player_exists(player) then return nil end
 	local ref = hb.get_hudtable(identifier).hudstate[player:get_player_name()]
+	if not ref then return nil end
 	-- Do not forget to update this chunk of code in case the state changes
 	local copy = {
 		hidden = ref.hidden,