Don't use `defer` in eth2_network to avoid https://github.com/nim-lang/Nim/issues/13899

beacon_chain/eth2_network.nim

@@ -392,15 +392,15 @@ proc sendNotificationMsg(peer: Peer, protocolId: string, requestBytes: Bytes) {.
     raise newException(TransmissionError, "Failed to open LibP2P stream")
 
   let stream = streamFut.read
-  defer:
+  try:
+    var s = memoryOutput()
+    s.appendVarint requestBytes.len.uint64
+    s.append requestBytes
+    let bytes = s.getOutput
+    await stream.write(bytes)
+  finally:
     await safeClose(stream)
 
-  var s = memoryOutput()
-  s.appendVarint requestBytes.len.uint64
-  s.append requestBytes
-  let bytes = s.getOutput
-  await stream.write(bytes)
-
 # TODO There is too much duplication in the responder functions, but
 # I hope to reduce this when I increse the reliance on output streams.
 proc sendResponseChunkBytes(responder: UntypedResponder, payload: Bytes) {.async.} =
@@ -442,19 +442,19 @@ proc makeEth2Request(peer: Peer, protocolId: string, requestBytes: Bytes,
     return none(ResponseMsg)
 
   let stream = streamFut.read
-  defer:
+  try:
+    # Send the request
+    var s = memoryOutput()
+    s.appendVarint requestBytes.len.uint64
+    s.append requestBytes
+    let bytes = s.getOutput
+    await stream.write(bytes)
+
+    # Read the response
+    return await stream.readResponse(ResponseMsg, deadline)
+  finally:
     await safeClose(stream)
 
-  # Send the request
-  var s = memoryOutput()
-  s.appendVarint requestBytes.len.uint64
-  s.append requestBytes
-  let bytes = s.getOutput
-  await stream.write(bytes)
-
-  # Read the response
-  return await stream.readResponse(ResponseMsg, deadline)
-
 proc init*[MsgType](T: type Responder[MsgType],
                     peer: Peer, conn: Connection): T =
   T(UntypedResponder(peer: peer, stream: conn))
@@ -546,38 +546,38 @@ proc handleIncomingStream(network: Eth2Node, conn: Connection,
 
   handleIncomingPeer(peer)
 
-  defer:
+  try:
+    let
+      deadline = sleepAsync RESP_TIMEOUT
+      msgBytes = await readMsgBytes(conn, false, deadline)
+
+    if msgBytes.len == 0:
+      await sendErrorResponse(peer, conn, ServerError, readTimeoutErrorMsg)
+      return
+
+    type MsgRec = RecType(MsgType)
+    var msg: MsgRec
+    try:
+      msg = decode(Format, msgBytes, MsgRec)
+    except SerializationError as err:
+      await sendErrorResponse(peer, conn, err, msgName, msgBytes)
+      return
+    except Exception as err:
+      # TODO. This is temporary code that should be removed after interop.
+      # It can be enabled only in certain diagnostic builds where it should
+      # re-raise the exception.
+      debug "Crash during serialization", inputBytes = toHex(msgBytes), msgName
+      await sendErrorResponse(peer, conn, ServerError, err.msg)
+      raise err
+
+    try:
+      logReceivedMsg(peer, MsgType(msg))
+      await callUserHandler(peer, conn, msg)
+    except CatchableError as err:
+      await sendErrorResponse(peer, conn, ServerError, err.msg)
+  finally:
     await safeClose(conn)
 
-  let
-    deadline = sleepAsync RESP_TIMEOUT
-    msgBytes = await readMsgBytes(conn, false, deadline)
-
-  if msgBytes.len == 0:
-    await sendErrorResponse(peer, conn, ServerError, readTimeoutErrorMsg)
-    return
-
-  type MsgRec = RecType(MsgType)
-  var msg: MsgRec
-  try:
-    msg = decode(Format, msgBytes, MsgRec)
-  except SerializationError as err:
-    await sendErrorResponse(peer, conn, err, msgName, msgBytes)
-    return
-  except Exception as err:
-    # TODO. This is temporary code that should be removed after interop.
-    # It can be enabled only in certain diagnostic builds where it should
-    # re-raise the exception.
-    debug "Crash during serialization", inputBytes = toHex(msgBytes), msgName
-    await sendErrorResponse(peer, conn, ServerError, err.msg)
-    raise err
-
-  try:
-    logReceivedMsg(peer, MsgType(msg))
-    await callUserHandler(peer, conn, msg)
-  except CatchableError as err:
-    await sendErrorResponse(peer, conn, ServerError, err.msg)
-
 proc handleOutgoingPeer*(peer: Peer): Future[void] {.async.} =
   let network = peer.network