UnitAI error code being displayed

[Langbart]

When playing a game on Alpha 25b [25860], some errors occurred and even when viewing the replay with and without mods, the error remains the same.

0 A.D. (0.0.25) Main log (warnings and errors only)
ERROR: JavaScript error: simulation/components/UnitAI.js line 6143 Failed to construct Vector3D object

ERROR: Failed to call ProcessCommand() global script function

Engine exited successfully on 2021-11-10 at 21:53:01 with 1604 message(s), 2 error(s) and 0 warning(s).

The error is displayed only once after about 10 seconds in the game. I will attach the replay as a zip file, I have never seen this error before.

​Line 6143 in Unitai.js at [25860]

Line
6137	UnitAI.prototype.RememberTargetPosition = function(orderData)
6138	{
6139	if (!orderData)
6140	orderData = this.order.data;
6141	let cmpPosition = Engine.QueryInterface(orderData.target, IID_Position);
6142	if (cmpPosition && cmpPosition.IsInWorld())
6143	orderData.lastPos = cmpPosition.GetPosition();
6144	};

[Langbart]

Adding the referenced line of code from the error to the description.

[Freagarach]

The problem is entity 408 (of player 7) trying to attack entity 425 (a chicken) whilst garrisoned. I have to investigate further. I mean, I have no clue why it can't construct a vector, but it seems the entity is in some kind of infinite loop. It sounds easy enough to reproduce on SVN with some replay modding.

[Freagarach]

No modding needed, merely a queued gather order.

[Freagarach]

In [26044]:

Fix infinite loop when queuing a gather order after garrison.

There was an infinite loop:
Order.Gather -> MustKill (L497) -> PushOrderFront(Attack) (L526) -> NotInRange (L410) -> NotAbleToMove, thus finish order (L426/427) -> Restart from Order.Gather.

We do two things here:

• Assume we don't have vision when garrisoned, which is not a bad assumption.
• Check the range and if we are not able to move and not in range, finish the order.

Introduced in: r25030 / rP25030
Reported by: @Langbart
Differential revision: ​​https://code.wildfiregames.com/D4349
Fixes: #6377
Tested by: @Langbart
Comments by: @Silier, @Stan