Imaginary friend unties a horse [dialogue]

[hexagonrecursion]

Describe the bug

This bug can be triggered in two different ways. I'll report them separately because I expect the fix to require changes to two different places in the code. See also #54367

When you tell an NPC to mount up, she or he finds a horse, unties it and rides it. This currently works even if the NPC is a hallucination.

Steps to reproduce

1. Get an imaginary friend
   1. Debug add effect "hallu" 20000 not permanent
   2. Walk around until you hallucinate an NPC. This may take a while. I do not know how to make this quick.
   3. Verify that you have met a hallucination and not a real NPC. Debug -> player -> edit player / NPC -> Status Window. In the top left corner it should say "John Doe | Male | Hallucination" (the name and gender are randomized, but the "| Hallucination" tag is always present)
   4. (optional) save, quit and backup your world
   5. Befriend the NPC. This may take a few tries. Note: I did not use debug mind control out of concern that it might interfere with the experiment
2. Spawn a horse
3. [a]ctivate cattle fodder
4. Use a short rope (id: rope_6) to tie the horse. Optionally: trigger Leashing a horse may cause items to dissappear #54365
5. (optional) use debug to delete all items from the NPC and make her wear a backpack - this allows you to monitor the NPC inventory contents later
6. Walk a short distance away. See that the horse stays where you left it
7. Talk your imaginary friend -> There is something I want you to do -> find a horse and mount up
8. The NPC proceeds to walk to the horse, untie and ride it
9. The rope with its contents (see Leashing a horse may cause items to dissappear #54365) ends up in the inventory of the NPC and is lost when the hallucination ends

Expected behavior

A figment of your imagination should not be able to untie a real rope.

Screenshots

No response

Versions and configuration

• OS: Linux
  • OS Version: LSB Version: :core-4.1-amd64:core-4.1-noarch; Distributor ID: Fedora; Description: Fedora release 34 (Thirty Four); Release: 34; Codename: ThirtyFour;
• Game Version: c8a49e1 [64-bit]
• Graphics Version: Tiles
• Game Language: English [en]
• Mods loaded: [
  Dark Days Ahead [dda],
  Disable NPC Needs [no_npc_food],
  Graphical Overmap [Graphical_Overmap]
  ]

Additional context

Related: #53677