refactor: update meterRegistry usage to Option type and improve formatting

modules/official-bots/src/main/scala/de/nowchess/bot/logic/AlphaBetaSearch.scala

@@ -15,7 +15,7 @@ final class AlphaBetaSearch(
     tt: TranspositionTable = TranspositionTable(),
     weights: Evaluation,
     numThreads: Int = Runtime.getRuntime.availableProcessors,
-    meterRegistry: MeterRegistry = null,
+    meterRegistry: Option[MeterRegistry] = None,
 ):
 
   private val INF                  = Int.MaxValue / 2
@@ -108,9 +108,10 @@ final class AlphaBetaSearch(
     result
 
   private def recordSearchMetrics(depthReached: Int): Unit =
-    if meterRegistry != null then
-      meterRegistry.summary("nowchess.bot.search.nodes").record(nodeCount.get().toDouble)
-      meterRegistry.summary("nowchess.bot.search.depth").record(depthReached.toDouble)
+    meterRegistry.foreach { mr =>
+      mr.summary("nowchess.bot.search.nodes").record(nodeCount.get().toDouble)
+      mr.summary("nowchess.bot.search.depth").record(depthReached.toDouble)
+    }
 
   private def isOutOfTime: Boolean =
     System.currentTimeMillis - timeStartMs.get >= timeLimitMs.get

modules/official-bots/src/main/scala/de/nowchess/bot/service/OfficialBotService.scala

@@ -19,11 +19,11 @@ import java.util.function.Consumer
 class OfficialBotService:
 
   // scalafix:off DisableSyntax.var
-  @Inject var redis: RedisDataSource         = uninitialized
-  @Inject var redisConfig: RedisConfig       = uninitialized
-  @Inject var objectMapper: ObjectMapper     = uninitialized
-  @Inject var botController: BotController   = uninitialized
-  @Inject var meterRegistry: MeterRegistry   = uninitialized
+  @Inject var redis: RedisDataSource       = uninitialized
+  @Inject var redisConfig: RedisConfig     = uninitialized
+  @Inject var objectMapper: ObjectMapper   = uninitialized
+  @Inject var botController: BotController = uninitialized
+  @Inject var meterRegistry: MeterRegistry = uninitialized
   // scalafix:on DisableSyntax.var
 
   private val terminalStatuses =