face: more robust handling of multicast face creation errors

Refs: #5030, #5297
Change-Id: I3ca985498d9d3756cbff94873063f3734bcea288
diff --git a/daemon/face/unix-stream-factory.hpp b/daemon/face/unix-stream-factory.hpp
index 8b044d4..76bbfc9 100644
--- a/daemon/face/unix-stream-factory.hpp
+++ b/daemon/face/unix-stream-factory.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2014-2022,  Regents of the University of California,
+ * Copyright (c) 2014-2023,  Regents of the University of California,
  *                           Arizona Board of Regents,
  *                           Colorado State University,
  *                           University Pierre & Marie Curie, Sorbonne University,
@@ -31,7 +31,8 @@
 
 namespace nfd::face {
 
-/** \brief Protocol factory for stream-oriented Unix sockets.
+/**
+ * \brief Protocol factory for stream-oriented Unix sockets.
  */
 class UnixStreamFactory final : public ProtocolFactory
 {
@@ -48,7 +49,7 @@
    * will be created.  The second call will just retrieve the existing
    * channel.
    *
-   * \returns always a valid pointer to a UnixStreamChannel object,
+   * \returns Always a valid pointer to a UnixStreamChannel object,
    *          an exception will be thrown if the channel cannot be created.
    */
   shared_ptr<UnixStreamChannel>