Fix child lookups, cache keys and loadstring

`loadstring` was removed in Lua 5.2, `load` takes a string the same way.

Warp gui child lookups are optional, so they use the same assert the
rest of the repo does.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

exp_legacy/module/expcore/roles.lua

@@ -894,7 +894,7 @@ role:set_permission_group('Admin')
 function Roles._prototype:set_permission_group(name, use_factorio_api)
     ExpUtil.assert_not_runtime()
     if use_factorio_api then
-        self.permission_group = { true, name }
+        self.permission_group = { true, name } --[[@as [boolean, string] ]]
     else
         local group = Groups.get_group_by_name(name)
         if not group then return end

exp_legacy/module/modules/gui/warp-list.lua

@@ -291,9 +291,13 @@ local confirm_edit_button = Gui.define("confirm_edit_button")
     }
     :style(Styles.sprite22)
     :on_click(function(def, player, element)
-        local warp_id = element.parent.caption
+        local parent = assert(element.parent)
-        local warp_name = element.parent.parent["name-" .. warp_id][warp_textfield.name].text
+        local grandparent = assert(parent.parent)
-        local warp_icon = element.parent.parent["icon-" .. warp_id][warp_icon_editing.name].elem_value --[[@as SignalID]]
+        local warp_id = parent.caption --[[@as string]]
+        local name_flow = assert(grandparent["name-" .. warp_id])
+        local icon_flow = assert(grandparent["icon-" .. warp_id])
+        local warp_name = assert(name_flow[warp_textfield.name]).text
+        local warp_icon = assert(icon_flow[warp_icon_editing.name]).elem_value --[[@as SignalID]]
         if warp_icon.type == nil then warp_icon.type = "item" end
         Warps.set_editing(warp_id, player.name)
         Warps.update_warp(warp_id, warp_name, warp_icon, player.name)
@@ -778,7 +782,7 @@ Event.on_nth_tick(math.floor(60 / config.update_smoothing), function()
         end
 
         -- Check if the force has any warps
-        local closest_warp = nil
+        local closest_warp = nil --- @type { warp_id: string, name: string }?
         local closest_distance = nil
         if #warp_ids > 0 then
             local surface = player.surface

exp_scenario/module/gui/debug/model.lua

@@ -4,7 +4,7 @@ local ExpUtil = require("modules/exp_util")
 local concat = table.concat
 local inspect = table.inspect
 local pcall = pcall
-local loadstring = loadstring --- @diagnostic disable-line
+local loadstring = load
 local rawset = rawset
 
 local Public = {}

exp_scenario/module/gui/science_production.lua

@@ -327,7 +327,7 @@ function Elements.science_table.refresh_row(science_table, row_data)
     Elements.production_label.refresh(row.used, row_data.used)
 end
 
-do local _row_data = {} --- @type table<string, { [string]: ExpGui_ScienceProduction.elements.science_table.row_data }>
+do local _row_data = {} --- @type table<string, table<number, ExpGui_ScienceProduction.elements.science_table.row_data>>
     --- Refresh the production tables for all online players
     function Elements.science_table.refresh_online()
         -- Refresh the row data for online forces