= akka: correctly handle invoke errors while processing system messages, fixes #184.

1 files changed, 6 insertions, 1 deletions

diff --git a/kamon-akka/src/main/scala/kamon/akka/instrumentation/ActorCellInstrumentation.scala b/kamon-akka/src/main/scala/kamon/akka/instrumentation/ActorCellInstrumentation.scala
index deb43499..bfcc0ed0 100644
--- a/kamon-akka/src/main/scala/kamon/akka/instrumentation/ActorCellInstrumentation.scala
+++ b/kamon-akka/src/main/scala/kamon/akka/instrumentation/ActorCellInstrumentation.scala
@@ -117,7 +117,12 @@ class ActorCellInstrumentation {
 
     // In case that this actor is behind a router, count the errors for the router as well.
     val envelope = cell.currentMessage.asInstanceOf[RouterAwareEnvelope]
-    envelope.routerMetricsRecorder.map(_.errors.increment())
+    if (envelope ne null) {
+      // The ActorCell.handleInvokeFailure(..) method is also called when a failure occurs
+      // while processing a system message, in which case ActorCell.currentMessage is always
+      // null.
+      envelope.routerMetricsRecorder.map(_.errors.increment())
+    }
   }
 }