Handle create_character failures in inventory sync (#975)

ensure_character asserted on player.create_character() returning false
without any context (#912). The most likely trigger is the player being
physically inside a space platform hub (or otherwise stuck in remote view)
on the destination server: the character in the hub is destroyed while
downloading and the god controller ends up on the platform surface where
a character can not be created.

- Explicitly exit remote view and move the god controller off platform
  surfaces before create_character; restore_position re-enters the platform
- Include controller/surface/connection state in the error message
- On deserialization failure treat the player as a temporary inventory
  (sync = false) so the incomplete state is not uploaded over synced data
- Release the acquisition on leave when nothing is uploaded so the player
  is not left "busy" on other instances

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

plugins/inventory_sync/module/inventory_sync.lua

@@ -314,15 +314,20 @@ function inventory_sync.sync_player(acquire_response)
 end
 
 function inventory_sync.finish_download(player, finished_record)
+	local script_data = get_script_data()
+	script_data.finished_downloads[player.name] = nil
+	local player_record = script_data.players[player.name]
+
 	local status, result = xpcall(inventory_sync.deserialize_player, debug.traceback, player, finished_record)
 	if not status then
 		log("ERROR: Deserializing player " .. player.name .. " failed: " .. result)
 		player.print("ERROR: Deserializing player data failed: " .. result)
+		-- Treat this as a temporary inventory so the incomplete state is not uploaded over the synced data
+		player_record.dirty = true
+		player_record.sync = false
+		return
 	end
-	local script_data = get_script_data()
-	script_data.finished_downloads[player.name] = nil
 
-	local player_record = script_data.players[player.name]
 	player_record.dirty = true
 	player_record.sync = true
 	player_record.generation = finished_record.generation
@@ -380,6 +385,8 @@ inventory_sync.events[defines.events.on_pre_player_left_game] = function(event)
 	end
 
 	if not player_record.dirty or not player_record.sync then
+		-- Nothing to upload, release the acquisition so other instances are not blocked
+		clusterio_api.send_json("inventory_sync_release", { player_name = player.name })
 		return
 	end
 

plugins/inventory_sync/module/serialize.lua

@@ -7,6 +7,8 @@ local serialize = {}
 local v2_logistic_api = compat.version_ge("2.0.0")
 local v2_storage_api = compat.version_ge("2.0.0")
 local v2_remote_controller = compat.version_ge("2.0.0")
+local v2_space_platform = compat.version_ge("2.0.0")
+local v2_exit_remote_view = compat.version_ge("2.0.56")
 local recipe_notifications_api = compat.version_ge("2.0.67")
 local v2_0_quick_bar_api = compat.version_ge("2.0.0")
 local v2_1_quick_bar_api = compat.version_ge("2.1.0")
@@ -666,6 +668,23 @@ function serialize.serialize_player(player, failed_deserialization)
 	return serialized
 end
 
+--- Find a surface characters can exist on, used when the player is on a space platform surface
+--- @param platform LuaSpacePlatform
+--- @return LuaSurface
+local function find_planet_surface(platform)
+	local location = platform.space_location
+	local planet = location and game.planets[location.name]
+	if planet and planet.surface then
+		return planet.surface
+	end
+	for _, surface in pairs(game.surfaces) do
+		if not surface.platform then
+			return surface
+		end
+	end
+	error("No surface found which can hold a character")
+end
+
 --- Ensure a player has a character, works from any controller type
 --- @param player LuaPlayer
 --- @return LuaEntity
@@ -676,13 +695,32 @@ local function ensure_character(player)
 		return character
 	end
 
+	-- Exit remote view before switching controllers, this can fail if the player is on a platform
+	if v2_exit_remote_view and player.controller_type == defines.controllers.remote then
+		player.exit_remote_view()
+	end
+
 	-- Switch to god controller if create_character would fail
 	if player.controller_type ~= defines.controllers.god then
 		player.set_controller{ type = defines.controllers.god }
 	end
 
+	-- Characters can not be created on platform surfaces, restore_position will move them back into the hub
+	local surface = player.surface
+	if v2_space_platform and surface.platform then
+		local planet_surface = find_planet_surface(surface.platform)
+		player.teleport(player.force.get_spawn_position(planet_surface), planet_surface)
+	end
+
 	-- Create and return the character
-	assert(player.create_character(), "Failed to create character")
+	if not player.create_character() then
+		error(string.format(
+			"Failed to create character (controller: %s, physical: %s, surface: %s, connected: %s, driving: %s)",
+			controller_to_name[player.controller_type],
+			v2_remote_controller and controller_to_name[player.physical_controller_type] or "n/a",
+			player.surface.name, tostring(player.connected), tostring(player.driving)
+		))
+	end
 	return player.character
 end