Fix bug with metrics scraping

beacon_node/http_server/src/key.rs

@@ -1,3 +1,4 @@
+use crate::metrics::LocalMetrics;
 use beacon_chain::{BeaconChain, BeaconChainTypes};
 use iron::typemap::Key;
 use prometheus::Registry;
@@ -17,3 +18,9 @@ pub struct MetricsRegistryKey;
 impl Key for MetricsRegistryKey {
     type Value = Registry;
 }
+
+pub struct LocalMetricsKey;
+
+impl Key for LocalMetricsKey {
+    type Value = LocalMetrics;
+}