Properly handle starting page again

mods/rp_crafting/api.lua

@@ -4,6 +4,8 @@ local S = minetest.get_translator("rp_crafting")
 local MODE_CRAFTABLE = 1 -- crafting guide mode, show all recipes (default)
 local MODE_GUIDE = 2 -- craftable mode, only show recipes craftable from input slots
 
+local mod_creative = minetest.get_modpath("rp_creative") ~= nil
+
 --
 -- API
 --
@@ -424,13 +426,16 @@ function crafting.get_formspec(name, select_craft_id)
 
    return form
 end
-
 rp_formspec.register_page("rp_crafting:crafting", form)
 rp_formspec.register_invpage("rp_crafting:crafting", {
-	is_startpage = function(pname)
-		return true
-	end,
 	get_formspec = crafting.get_formspec,
+	_is_startpage = function(pname)
+		if mod_creative and minetest.is_creative_enabled(pname) then
+			return false
+		else
+			return true
+		end
+	end,
 })
 
 rp_formspec.register_invtab("rp_crafting:crafting", {

mods/rp_creative/init.lua

@@ -260,6 +260,13 @@ end
 rp_formspec.register_page("rp_creative:creative", form)
 rp_formspec.register_invpage("rp_creative:creative", {
 	get_formspec = creative.get_formspec,
+	_is_startpage = function(pname)
+		if minetest.is_creative_enabled(pname) then
+			return true
+		else
+			return false
+		end
+	end,
 })
 if minetest.is_creative_enabled("") then
 	rp_formspec.register_invtab("rp_creative:creative", {

mods/rp_formspec/init.lua

@@ -403,14 +403,29 @@ minetest.register_on_joinplayer(
       -- Initialize player formspec and set initial invpage
       player:set_formspec_prepend(formspec_prepend)
       local pname = player:get_player_name()
+      local first_page
       for invpagename,def in pairs(rp_formspec.registered_invpages) do
-          if def.is_startpage and def.is_startpage(pname) then
+          if not first_page then
+             first_page = invpagename
+          end
+          -- _is_startpage returns true if this page
+          -- is a startpage, false otherwise.
+          -- As this function only makes sense within the context of a game,
+          -- it is undocumented in API.md.
+          if def._is_startpage and def._is_startpage(pname) then
              rp_formspec.set_current_invpage(player, invpagename)
+             break
           end
       end
       -- Fallback invpage
       if not rp_formspec.get_current_invpage(player) then
-         rp_formspec.set_current_invpage(player, "rp_formspec:inventory")
+         if first_page then
+            -- First invpage of the pairs() above (kinda unpredicable tho)
+            rp_formspec.set_current_invpage(player, first_page)
+	 else
+            -- Empty inventory fallback page if no invpages registered
+            rp_formspec.set_current_invpage(player, "rp_formspec:inventory")
+         end
       end
 end)