opcode #38 in 3.2.4.beta1 (regression from 3.2.3.stable)

[Error7Studios]

Godot version:
3.2.4.beta1

OS/device including version:
Windows 10

Issue description:
opcode 38 (report please)

<C++ Source> modules/gdscript
E 0:00:00.998   call: Condition ' !base_type ' is true. Breaking..:
  <C++ Source>  modules/gdscript/gdscript_function.cpp:837 @ call()

Steps to reproduce:
Could not reproduce in a new project.

Minimal reproduction project:
A huge project of spaghetti code.
Tried to reduce it down to a minimal project, but everything breaks when I try, so this is all I can provide, sorry.
opcode 38 Bug - 1.zip

[Rubonnek]

Welp, I was able to reproduce. For some reason executing the project through the Editor does not generate the warning. Interesting.

SCRIPT ERROR: PlayerInventoryNamesMenu.create_inventory_object_counts_menu: Internal Script Error! - opcode #38 (report please).
   At: res://Scenes/PlayerInventoryNamesMenu/PlayerInventoryNamesMenu.gd:24.

[Error7Studios]

Was able to reproduce by following the steps provided in #43042.
Closing, since I've added a screenshot to that issue that adds more information.