fix: clean up code formatting and improve error handling in gRPC server and failover service

modules/coordinator/src/main/scala/de/nowchess/coordinator/grpc/CoordinatorGrpcServer.scala

@@ -127,7 +127,8 @@ class CoordinatorGrpcServer extends CoordinatorServiceGrpc.CoordinatorServiceImp
         _ =>
           val response = DrainInstanceResponse.newBuilder().setGamesMigrated(gamesBefore).build()
           responseObserver.onNext(response)
-          responseObserver.onCompleted(),
+          responseObserver.onCompleted()
+        ,
         ex =>
           log.warnf(ex, "Drain failed for %s", instanceId)
           responseObserver.onError(ex),

modules/coordinator/src/main/scala/de/nowchess/coordinator/service/FailoverService.scala

@@ -122,14 +122,17 @@ class FailoverService:
     log.infof("Cleaned up games set for instance %s", instanceId)
 
   private def waitForHealthyInstanceAsync(): Uni[InstanceMetadata] =
-    Uni.createFrom().deferred(() =>
+    Uni
-      instanceRegistry.getAllInstances
+      .createFrom()
-        .filter(_.state == "HEALTHY")
+      .deferred(() =>
-        .sortBy(_.subscriptionCount)
+        instanceRegistry.getAllInstances
-        .headOption match
+          .filter(_.state == "HEALTHY")
+          .sortBy(_.subscriptionCount)
+          .headOption match
           case Some(inst) => Uni.createFrom().item(inst)
-          case None       => Uni.createFrom().failure(new RuntimeException("no healthy instance"))
+          case None       => Uni.createFrom().failure(new RuntimeException("no healthy instance")),
-    ).onFailure()
+      )
+      .onFailure()
       .retry()
       .withBackOff(Duration.ofMillis(500))
       .expireIn(config.failoverWaitTimeout.toMillis)

modules/coordinator/src/main/scala/de/nowchess/coordinator/service/HealthMonitor.scala

@@ -133,8 +133,7 @@ class HealthMonitor:
                 action match
                   case Watcher.Action.DELETED =>
                     handlePodGone(pod)
-                  case Watcher.Action.MODIFIED
+                  case Watcher.Action.MODIFIED if Option(pod.getMetadata.getDeletionTimestamp).isDefined =>
-                      if Option(pod.getMetadata.getDeletionTimestamp).isDefined =>
                     handlePodTerminating(pod)
                   case _ => ()
 
@@ -142,11 +141,10 @@ class HealthMonitor:
                 Option(cause).foreach { ex =>
                   log.warnf(ex, "Pod watch closed, restarting")
                   startPodWatch()
-                }
+                },
             )
           log.info("Pod watch started")
-        catch
+        catch case ex: Exception => log.warnf(ex, "Failed to start pod watch")
-          case ex: Exception => log.warnf(ex, "Failed to start pod watch")
 
   private def isPodReady(pod: Pod): Boolean =
     Option(pod.getStatus)