[PATCH] SwitchMarketOrder error

[elexis]

This error occured when a player was defeated with r18581:

ERROR: JavaScript error: simulation/components/UnitAI.js line 5222
TypeError: this.order is undefined
  UnitAI.prototype.SwitchMarketOrder@simulation/components/UnitAI.js:5222:1
  Trader.prototype.SwitchMarket@simulation/components/Trader.js:260:3
  Mirage.prototype.UpdateTraders@simulation/components/Mirage.js:182:3
  Mirage.prototype.OnVisibilityChanged@simulation/components/Mirage.js:196:3

Not sure if it's that, but noone investigated this case yet as far as I know:

2016-06-03-QuakeNet-#0ad-dev.log:22:17 <@leper> another possible issue with that commit: what happens if one of the markets changes owner right before the trade is done?

[elexis]

Error occurs on turn 9015

[elexis]

• How can we reproduce the bug? Was it related to that comment?

It's fully reproducible in the replay you provided. And no relation with the comment which imo is already taken into account. The problem is when changing ownership, UnitAI does a Stop which stops the trading route, but the route content in the Trader component was not reset (now done with the StopTrading). In addition, WorkOrders were not reset (now done).

• Perhaps there could be some test that ensures that a trade cart has no more work orders after ownership change etc.?

Not needed after the patch.

• This one hunk could become return this.MoveToPoint(point.x, point.z)) || this.MoveToMarket(targetMarket)

Yes, this should work too.

[mimo]

Sorry, I edited previous elexis post instead of replying to it :)

[elexis]

In 18749:

Fix a trade cart UnitAI error occuring rarely on defeat, by clearing the traderoute if the trader changed ownership. Patch by mimo, fixes #4131.

Also simplify MoveToMarket.

[elexis]

Thanks for the patch mimo! Sorry that we couldn't get to review this sooner.