Player kills hostile animal owned by AI - errors about orderData undefined

[Norse_Harold]

Summary: If a player kills a wild animal that is hostile and owned by an AI-controlled player then a large amount of warnings and errors appear.

Versions known to be affected: release version alpha 0.0.26, dev a27 version r27624, dev a27 version rc1 r27645.

Expected results: Either it is not possible for the scenario editor to create a map that causes these symptoms, or the errors do not occur when an AI-owned hostile animal is killed.

Actual results: A large amount of warning and error messages appear. Excerpts are attached.

Steps to reproduce the symptoms:

• Extract the "Flatland with player-owned bears.zip" file to the mods/user/maps/scenarios folder in your 0ad game data folder.
• Load the scenario "Flatland with player-owned bears". Slot yourself as player 1, and slot 1 AI in the remaining slots.
• Use the cheat "gift from the gods" (type it in chat) to get p3, a lot of resources, and fast building.
• Build a stable and produce 50 cavalry.
• Send the cavalry to attack AI-controlled player 2, toward the east (3 o'clock).
• After fighting with an AI-controlled opponent and killing one of its bears, the error should appear continuously until the AI player is neutralized.

Computing Environnment (OS brand and version, hardware, relevant driver version and other software versions): The OS I have used for testing is Linux. The problem does not seem to be hardware dependent, as others have observed the same symptoms.

Relevant logs, files that reproduce the symptoms, screenshots, etc.: (attached)

Credits: First reported by seregadushka and Alexandra in ​this forum post.

[Norse_Harold]

The map "Flatland with player-owned bears"

[Norse_Harold]

Errors when using "Flatland with player-owned bears" map

[Norse_Harold]

The map "Winter Is Coming" with AI player-owned bears and wolfhounds

[Norse_Harold]

Errors when using "Winter Is Coming" map (with AI player-owned bears and wolfhounds)

[Freagarach]

In 28025:

[PetraAI] - Fix resources (dead animals) coming in the defense army.

When a wild animal was in a defenseArmy and it was killed, its resource got into the army as well. This caused a call to GetUnitAIOrder data which was undefined for the resource.
Fixed by checking for UnitAI-ness and also for attack-ability whilst at it.

Reported by @seregadushka at the forums: ​https://wildfiregames.com/forum/topic/110098-petra-error-winter-is-coming5/.

Investigated and MWE by @Norse_Harold.
Fixes #6899