Update matchmaking/attributes-and-signals.md (#1272)

## Changes

Issues I missed in #1271

- Fix formatting for line 229
- Instead of `error`, use `errorMessage`, as this collides with the
[error](https://create.roblox.com/docs/reference/engine/globals/LuaGlobals#error)
global (per
[pcall](https://create.roblox.com/docs/reference/engine/globals/LuaGlobals#pcall)
example)
- Fixed invalid syntax (trying to assign to variable inside if
statement)

## Checks

By submitting your pull request for review, you agree to the following:

- [x] This contribution was created in whole or in part by me, and I
have the right to submit it under the terms of this repository's open
source licenses.
- [x] I understand and agree that this contribution and a record of it
are public, maintained indefinitely, and may be redistributed under the
terms of this repository's open source licenses.
- [x] To the best of my knowledge, all proposed changes are accurate.

---------

Author: ari-party

content/en-us/matchmaking/attributes-and-signals.md

@@ -211,12 +211,12 @@ local DataStoreService = game:GetService("DataStoreService")
 local eloStore = DataStoreService:GetDataStore("PlayerElo")
 
 function onMatchEnded(players: {Player}, winners: {Player}, losers: {Player})
-  for _, player in players do
-    local updatedElo = CalculateUpdatedElo(player, winners, losers)
-    local success, errorMessage = pcall(function()
-      eloStore:SetAsync(player.UserId, updatedElo)
-    end)
-  end
+	for _, player in players do
+		local updatedElo = CalculateUpdatedElo(player, winners, losers)
+		local success, errorMessage = pcall(function()
+			eloStore:SetAsync(player.UserId, updatedElo)
+		end)
+	end
 end
 ```
 
@@ -225,30 +225,28 @@ local MatchmakingService = game:GetService("MatchmakingService")
 local RunService = game:GetService("RunService")
 
 if RunService:IsStudio() then
-  -- Sets up initial attributes and schema for testing
-  MatchmakingService:InitializeServerAttributesForStudio(
-  {
-    Level = "Advanced",
-    Elo = 123.456,
-    TrainingMode = true
-  })
+	-- Sets up initial attributes and schema for testing
+	MatchmakingService:InitializeServerAttributesForStudio({
+		Level = "Advanced",
+		Elo = 123.456,
+		TrainingMode = true
+	})
 end
 
 -- Retrieves the Level attribute
-local currentLevel, error = MatchmakingService:GetServerAttribute("Level")
-
-if error then
-  print(error)
+local currentLevel, errorMessage = MatchmakingService:GetServerAttribute("Level")
+if errorMessage then
+	warn(errorMessage)
 else
-  print("Current level: " .. currentLevel)
+	print("Current level: " .. currentLevel)
 end
 
 -- Updates the Level attribute value to Advanced
-local success, error = MatchmakingService:SetServerAttribute("Level", "Advanced")
+local success, errorMessage = MatchmakingService:SetServerAttribute("Level", "Advanced")
 if not success then
-  print("Failed to update server attribute [Level] to [Advanced] due to error: " .. error)
+	warn("Failed to update server attribute [Level] to [Advanced] due to error: " .. errorMessage)
 else
-  print("Successfully set [Level] to [Advanced]")
+	print("Successfully set [Level] to [Advanced]")
 end
 ```
 
@@ -386,21 +384,21 @@ local score = math.min(diff / max_relevant_difference, 1)
 The score is 1 when the server's attribute value (for example, Game Mode) is equal to the player's attribute value (for example, Preferred Game Mode). Otherwise, the signal score is 0.
 
 ```lua title="Joining player formula for server categorical signal"
-if server_{attribute_name} = joining_player_{attribute_name} then
-  return 1 
+if server_{attribute_name} == joining_player_{attribute_name} then
+	return 1 
 else
-  return 0 
+	return 0 
 end
 ```
 
 ```lua title="Joining player example for server categorical signal"
 local server_GameMode = "Survival"
 local joining_player_GameMode = "Survival"
 
-if server_GameMode = joining_player_GameMode then
-  return 1
+if server_GameMode == joining_player_GameMode then
+	return 1
 else
-  return 0
+	return 0
 end
 ```
 
@@ -409,19 +407,19 @@ end
 The score is 1 when the server's attribute value is equal to a constant value of true. Otherwise, the signal score is 0.
 
 ```lua title="Constant value formula for server categorical signal"
-if server_{attribute_name} = constant_value then
-  return 1 
+if server_{attribute_name} == constant_value then
+	return 1 
 else
-  return 0
+	return 0
 end
 ```
 
 ```lua title="Constant value example for server categorical signal"
 local server_GameNotStarted = true
 
-if server_GameNotStarted = true then
-  return 1
+if server_GameNotStarted == true then
+	return 1
 else
-  return 0
+	return 0
 end
 ```