Fix error when full share transfers units to a dead player

[lL1l1]

Issue

Reported on Discord. Replay 23190625.

WARNING: Error running lua script: ...aforever\replaydata\gamedata\lua.nx2\lua\aibrain.lua(498): bad argument #1 to `getn' (table expected, got no value)
         stack traceback:
         	[C]: in function `getn'
         	...aforever\replaydata\gamedata\lua.nx2\lua\aibrain.lua(498): in function <...aforever\replaydata\gamedata\lua.nx2\lua\aibrain.lua:479>
         	...aforever\replaydata\gamedata\lua.nx2\lua\aibrain.lua(526): in function `TransferUnitsToHighestBrain'
         	...aforever\replaydata\gamedata\lua.nx2\lua\aibrain.lua(608): in function <...aforever\replaydata\gamedata\lua.nx2\lua\aibrain.lua:440>

The game tried to transfer units to a defeated player which causes the TransferUnitsOwnership function to return nil, and TransferUnitsToBrain didn't handle this case before putting the results into table.getn.

Description of the proposed changes

Add a guard so that it puts an empty table into getn if the result is nil.

Testing done on the proposed changes

Running the replay again with the changes properly transfers the units after the player dies.
To run the replay with changes from your local repo, load the replay from the FAF client to unpack it, and then run the console command:

UI_Lua LaunchReplaySession('C:/ProgramData/FAForever/data/cache/temp.SCFAReplay')

Checklist

• Changes are annotated, including comments where useful
  • The TransferUnitsOwnership function has a proper return value of Unit[]?
• Changes are documented in the changelog for the next game version

[4z0t]

Overthinking. Put function result into a variable and check against nil.

[lL1l1]

Thanks, also I can use next() instead of table.getn > 0.

[4z0t]

Also bad idea. table.empty would be more understandable.

[4z0t]

I doublt table.empty accepts nil

[lL1l1]

It does accept nil:

fa/lua/system/utils.lua

Lines 59 to 62 in 2d1e06a

	function table.empty(t)
	if type(t) ~= 'table' then return true end
	return next(t) == nil
	end

[4z0t]

It does accept nil:

fa/lua/system/utils.lua

Lines 59 to 62 in 2d1e06a

	function table.empty(t)
	if type(t) ~= 'table' then return true end
	return next(t) == nil
	end

https://github.com/FAForever/fa/blob/develop/lua/simInit.lua#L25
Sim uses asm implementation.

[lL1l1]

Console command:

SimLua 
LOG('"table.empty":', table.empty, '"table.empty(nil)"', table.empty(nil))
LOG('"table.empty2":', table.empty2, '"table.empty2(nil)"', table.empty2(nil))

Output:

info: "table.empty":	function: 22180F28	"table.empty(nil)"	true
info: "table.empty2":	cfunction: 1AF80C00	"table.empty2(nil)"	true

[lL1l1]

Also debug.getinfo says that table.empty in Sim is sourced from /lua/system/utils.lua

[4z0t]

It is seems like a bug. Currently pending.

[4z0t]

#6439