tcp, pipe: don't assert on uv_accept() errors

It's possible for a new connection to be closed in the window between the
accept() syscall and the call to uv_accept(). Deal with it and move on, don't
assert.

src/pipe_wrap.cc

@@ -204,10 +204,7 @@ void PipeWrap::OnConnection(uv_stream_t* handle, int status) {
   PipeWrap* client_wrap =
       static_cast<PipeWrap*>(client_obj->GetPointerFromInternalField(0));
 
-  int r = uv_accept(handle, (uv_stream_t*)&client_wrap->handle_);
-
-  // uv_accept should always work.
-  assert(r == 0);
+  if (uv_accept(handle, (uv_stream_t*)&client_wrap->handle_)) return;
 
   // Successful accept. Call the onconnection callback in JavaScript land.
   Local<Value> argv[1] = { client_obj };

src/tcp_wrap.cc

@@ -366,10 +366,7 @@ void TCPWrap::OnConnection(uv_stream_t* handle, int status) {
     TCPWrap* client_wrap =
         static_cast<TCPWrap*>(client_obj->GetPointerFromInternalField(0));
 
-    int r = uv_accept(handle, (uv_stream_t*)&client_wrap->handle_);
-
-    // uv_accept should always work.
-    assert(r == 0);
+    if (uv_accept(handle, (uv_stream_t*)&client_wrap->handle_)) return;
 
     // Successful accept. Call the onconnection callback in JavaScript land.
     argv[0] = client_obj;