chore: list raised exceptions in utils module (#1252)

part of https://github.com/vacp2p/nim-libp2p/issues/962 effort.

libp2p/utils/future.nim

@@ -13,21 +13,25 @@ import chronos
 
 type AllFuturesFailedError* = object of CatchableError
 
-proc anyCompleted*[T](futs: seq[Future[T]]): Future[Future[T]] {.async.} =
+proc anyCompleted*[T](
+    futs: seq[Future[T]]
+): Future[Future[T]] {.async: (raises: [AllFuturesFailedError, CancelledError]).} =
   ## Returns a future that will complete with the first future that completes.
   ## If all futures fail or futs is empty, the returned future will fail with AllFuturesFailedError.
 
   var requests = futs
 
   while true:
-    if requests.len == 0:
+    var raceFut: Future[T]
+
+    try:
+      raceFut = await one(requests)
+      if raceFut.completed:
+        return raceFut
+    except ValueError:
       raise newException(
         AllFuturesFailedError, "None of the futures completed successfully"
       )
 
-    var raceFut = await one(requests)
-    if raceFut.completed:
-      return raceFut
-
     let index = requests.find(raceFut)
     requests.del(index)