feat(discv5): added find random nodes with predicate

apps/wakunode2/app.nim

@@ -682,13 +682,11 @@ proc startNode(node: WakuNode, conf: WakuNodeConf,
   except CatchableError:
     return err("failed to start waku node: " & getCurrentExceptionMsg())
 
-  # Start discv5 and connect to discovered nodes
+  # Start discv5 based discovery service (discovery loop)
   if conf.discv5Discovery:
-    try:
-      if not await node.startDiscv5():
-        error "could not start Discovery v5"
-    except CatchableError:
-      return err("failed to start waku discovery v5: " & getCurrentExceptionMsg())
+    let startDiscv5Res = await node.startDiscv5()
+    if startDiscv5Res.isErr():
+      return err("failed to start waku discovery v5: " & startDiscv5Res.error)
 
   # Connect to configured static nodes
   if conf.staticnodes.len > 0:

examples/v2/publisher.nim

@@ -66,8 +66,10 @@ proc setupAndPublish(rng: ref HmacDrbgContext) {.async.} =
     await node.start()
     await node.mountRelay()
     node.peerManager.start()
-    if not await node.startDiscv5():
-      error "failed to start discv5"
+
+    let discv5Res = await node.startDiscv5()
+    if discv5Res.isErr():
+      error "failed to start discv5", error= discv5Res.error
       quit(1)
 
     # wait for a minimum of peers to be connected, otherwise messages wont be gossiped

examples/v2/subscriber.nim

@@ -61,7 +61,9 @@ proc setupAndSubscribe(rng: ref HmacDrbgContext) {.async.} =
     await node.start()
     await node.mountRelay()
     node.peerManager.start()
-    if not await node.startDiscv5():
+
+    let discv5Res = await node.startDiscv5()
+    if discv5Res.isErr():
       error "failed to start discv5"
       quit(1)