eh cleanups (#1458)

current exception sometimes buggy in nim

beacon_chain/eth2_network.nim

@@ -280,9 +280,9 @@ proc openStream(node: Eth2Node,
   let protocolId = protocolId & (if peer.lacksSnappy: "ssz" else: "ssz_snappy")
   try:
     result = await dial(node.switch, peer.info.peerId, peer.info.addrs, protocolId)
-  except CancelledError:
-    raise
-  except CatchableError:
+  except CancelledError as exc:
+    raise exc
+  except CatchableError as exc:
     # TODO: LibP2P should raise a more specific exception here
     if peer.lacksSnappy == false:
       peer.lacksSnappy = true
@@ -290,7 +290,7 @@ proc openStream(node: Eth2Node,
             peer, protocolId
       return await openStream(node, peer, protocolId)
     else:
-      raise
+      raise exc
 
 proc init*(T: type Peer, network: Eth2Node, info: PeerInfo): Peer {.gcsafe.}
 

beacon_chain/mainchain_monitor.nim

@@ -321,7 +321,7 @@ proc getBlockNumber(p: DataProviderRef, hash: BlockHash): Future[Eth1BlockNumber
   except CatchableError as exc:
     notice "Failed to get Eth1 block number from hash",
       hash = $hash, err = exc.msg
-    raise
+    raise exc
 
 template readJsonField(j: JsonNode,
                        fieldName: string,

beacon_chain/peer_pool.nim

@@ -94,12 +94,12 @@ proc waitForEvent[A, B](pool: PeerPool[A, B], eventType: EventType,
         if not(fut1.finished):
           fut1.cancel()
         outgoingEvent(eventType).clear()
-    except CancelledError:
+    except CancelledError as exc:
       if not(fut1.finished):
         fut1.cancel()
       if not(fut2.finished):
         fut2.cancel()
-      raise
+      raise exc
   elif PeerType.Incoming in filter:
     await incomingEvent(eventType).wait()
     incomingEvent(eventType).clear()
@@ -497,13 +497,13 @@ proc acquire*[A, B](pool: PeerPool[A, B],
           doAssert(PeerFlags.Acquired notin item[].flags)
           item[].flags.incl(PeerFlags.Acquired)
           peers.add(item[].data)
-  except CancelledError:
+  except CancelledError as exc:
     # If we got cancelled, we need to return all the acquired peers back to
     # pool.
     for item in peers:
       pool.release(item)
     peers.setLen(0)
-    raise
+    raise exc
   result = peers
 
 proc acquireNoWait*[A, B](pool: PeerPool[A, B],