Segfault When accessing inventory

[shsorbom]

Description

When using Artemple map, accessing inventory Segfaults the game:

Thread 1 "falltergeist" received signal SIGSEGV, Segmentation fault.
0x00005555556cdedc in Falltergeist::UI::InventoryItem::render (this=0x555558655d50, eggTransparency=) at ./src/UI/InventoryItem.cpp:137
137 ./src/UI/InventoryItem.cpp: No such file or directory.
(gdb) frame
#0 0x00005555556cdedc in Falltergeist::UI::InventoryItem::render (this=0x555558655d50, eggTransparency=) at ./src/UI/InventoryItem.cpp:137
137 in ./src/UI/InventoryItem.cpp

Steps to Reproduce

1. Load the game on map Artemple
2. Click on Inventory
3. Segfault

System

• Falltergeist: commit b57b611

• Operating System: Debian Stretch
  -Version: GOG

[JanSimek]

Same thing as in #531 (comment)

A spear is created and added to the inventory by the artemple script, but then it is removed from the list of objects and player's inventory is left with a dangling pointer.