Sever tunnel links earlier

When we get an error on the tcp connection immediately sever the link to
the quic tunnel so that it doesn't keep trying to forward data to it.

llarp/quic/stream.hpp

@@ -242,7 +242,8 @@ namespace llarp::quic
     void
     data(std::shared_ptr<void> data);
 
-    // Variation of data() that holds the pointer in a weak_ptr instead of a shared_ptr.
+    // Variation of data() that holds the pointer in a weak_ptr instead of a shared_ptr.  (Note that
+    // setting this replaces data() and vice versa).
     void
     weak_data(std::weak_ptr<void> data);
 

llarp/quic/tunnel.cpp

@@ -56,7 +56,8 @@ namespace llarp::quic
     on_incoming_data(Stream& stream, bstring_view bdata)
     {
       auto tcp = stream.data<uvw::TCPHandle>();
-      assert(tcp);
+      if (!tcp) return; // TCP connection is gone, which would have already sent a stream close, so just drop it.
+
       std::string_view data{reinterpret_cast<const char*>(bdata.data()), bdata.size()};
       auto peer = tcp->peer();
       LogTrace(peer.ip, ":", peer.port, " ← lokinet ", buffer_printer{data});
@@ -90,7 +91,11 @@ namespace llarp::quic
       tcp.on<uvw::CloseEvent>([](auto&, uvw::TCPHandle& c) {
         // This fires sometime after we call `close()` to signal that the close is done.
         LogError("Connection closed to ", c.peer().ip, ":", c.peer().port, "; closing quic stream");
-        c.data<Stream>()->close();
+        if (auto stream = c.data<Stream>())
+        {
+          stream->close();
+          stream->data(nullptr);
+        }
         c.data(nullptr);
       });
       tcp.on<uvw::EndEvent>([](auto&, uvw::TCPHandle& c) {
@@ -109,10 +114,12 @@ namespace llarp::quic
             ":",
             tcp.peer().port,
             ", shutting down quic stream");
-        // Failed to open connection, so close the quic stream
-        auto stream = tcp.data<Stream>();
-        if (stream)
+        if (auto stream = tcp.data<Stream>())
+        {
           stream->close(tunnel::ERROR_TCP);
+          stream->data(nullptr);
+          tcp.data(nullptr);
+        }
         tcp.closeReset();
       });
       tcp.on<uvw::DataEvent>(on_outgoing_data);