Fix recently introduced errors for gRPC block prod

beacon_node/beacon_chain/src/beacon_chain.rs

@@ -371,6 +371,12 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
     }
     */
 
+    /// Returns a read-lock guarded `BeaconState` which is the `canonical_head` that has been
+    /// updated to match the current slot clock.
+    pub fn current_state(&self) -> RwLockReadGuard<BeaconState<T::EthSpec>> {
+        self.state.read()
+    }
+
     /// Returns a read-lock guarded `CheckPoint` struct for reading the head (as chosen by the
     /// fork-choice rule).
     ///

beacon_node/rpc/src/attestation.rs

@@ -34,7 +34,7 @@ impl<T: BeaconChainTypes> AttestationService for AttestationServiceInstance<T> {
         // verify the slot, drop lock on state afterwards
         {
             let slot_requested = req.get_slot();
-            let state = &self.chain.head().beacon_state;
+            let state = &self.chain.current_state();
 
             // Start by performing some checks
             // Check that the AttestionData is for the current slot (otherwise it will not be valid)

beacon_node/rpc/src/validator.rs

@@ -30,7 +30,7 @@ impl<T: BeaconChainTypes> ValidatorService for ValidatorServiceInstance<T> {
         trace!(self.log, "RPC request"; "endpoint" => "GetValidatorDuties", "epoch" => req.get_epoch());
 
         let spec = T::EthSpec::spec();
-        let state = &self.chain.head().beacon_state;
+        let state = &self.chain.current_state();
         let epoch = Epoch::from(req.get_epoch());
         let mut resp = GetDutiesResponse::new();
         let resp_validators = resp.mut_active_validators();