fix lua stack leak

res/content/base/scripts/hud.lua

@@ -3,14 +3,21 @@ local DROP_INIT_VEL = {0, 3, 0}
 
 function on_hud_open()
     input.add_callback("player.drop", function ()
+        for i=1,5 do
         local pid = hud.get_player()
         local pvel = {player.get_vel(pid)}
         local ppos = vec3.add({player.get_pos(pid)}, {0, 0.7, 0})
-        local throw_force = vec3.mul(player.get_dir(pid), DROP_FORCE)
+        local throw_force = vec3.mul(vec3.add(player.get_dir(pid), 
+        {
+            math.random() - 0.5,
+            math.random() - 0.5,
+            math.random() - 0.5
+        }), DROP_FORCE)
 
         local drop = entity.spawn("base:drop", ppos)
         drop.rigidbody:set_vel(vec3.add(throw_force, vec3.add(pvel, DROP_INIT_VEL)))
         drop.transform:set_rot(mat4.rotate(mat4.rotate(mat4.rotate({0, 1, 0}, math.random() * 360), 
             {1, 0, 0}, math.random() * 360), {0, 0, 1}, math.random() * 360))
+        end
     end)
 end

src/frontend/debug_panel.cpp

@@ -10,6 +10,7 @@
 #include "../graphics/render/WorldRenderer.hpp"
 #include "../logic/scripting/scripting.hpp"
 #include "../objects/Player.hpp"
+#include "../objects/Entities.hpp"
 #include "../physics/Hitbox.hpp"
 #include "../util/stringutil.hpp"
 #include "../voxels/Block.hpp"
@@ -83,6 +84,9 @@ std::shared_ptr<UINode> create_debug_panel(
         return L"chunks: "+std::to_wstring(level->chunks->chunksCount)+
                L" visible: "+std::to_wstring(level->chunks->visible);
     }));
+    panel->add(create_label([=]() {
+        return L"entities: "+std::to_wstring(level->entities->size());
+    }));
     panel->add(create_label([=](){
         const auto& vox = player->selection.vox;
         std::wstringstream stream;

src/logic/scripting/scripting.cpp

@@ -318,6 +318,7 @@ void scripting::on_entities_update() {
     auto L = lua::get_main_thread();
     lua::get_from(L, STDCOMP, "update", true);
     lua::call_nothrow(L, 0, 0);
+    lua::pop(L);
 }
 
 void scripting::on_ui_open(