Fix nrpc edge cases (#2692)

* fix: engineAPI unable to connect

* fix: pre-merge situation

nrpc/nrpc.nim

@@ -130,20 +130,18 @@ proc syncToEngineApi(conf: NRpcConf) {.async.} =
     # And exchange the capabilities for a test communication
     web3 = await engineUrl.newWeb3()
     rpcClient = web3.provider
-    data =
+
   try:
-        await rpcClient.exchangeCapabilities(
+    let data = await rpcClient.exchangeCapabilities(
       @[
-            "engine_forkchoiceUpdatedV1",
-            "engine_getPayloadBodiesByHash", "engine_getPayloadBodiesByRangeV1",
-            "engine_getPayloadV1", "engine_newPayloadV1",
+        "engine_forkchoiceUpdatedV1", "engine_getPayloadBodiesByHash",
+        "engine_getPayloadBodiesByRangeV1", "engine_getPayloadV1", "engine_newPayloadV1",
       ]
     )
+    notice "Communication with the EL Success", data = data
   except CatchableError as exc:
     error "Error Connecting to the EL Engine API", error = exc.msg
-        @[]
-
-  notice "Communication with the EL Success", data = data
+    quit(QuitFailure)
 
   # Get the latest block number from the EL rest api
   template elBlockNumber(): uint64 =
@@ -163,6 +161,12 @@ proc syncToEngineApi(conf: NRpcConf) {.async.} =
 
   notice "Current block number", number = currentBlockNumber
 
+  # Check for pre-merge situation
+  if currentBlockNumber <= lastEra1Block:
+    notice "Pre-merge, nrpc syncer works post-merge",
+      blocknumber = currentBlockNumber, lastPoWBlock = lastEra1Block
+    quit(QuitSuccess)
+
   # Load the latest state from the CL
   var
     (finalizedBlck, _) = client.getELBlockFromBeaconChain(
@@ -216,9 +220,7 @@ proc syncToEngineApi(conf: NRpcConf) {.async.} =
           )
           debug "Making new payload call for Deneb"
           payloadResponse = await rpcClient.newPayload(
-            payload,
-            versioned_hashes,
-            forkyBlck.message.parent_root.to(Hash32),
+            payload, versioned_hashes, forkyBlck.message.parent_root.to(Hash32)
           )
         notice "Payload status", response = payloadResponse