src: fix coverity report

Fix coverity report about possibly dereferencing
a null. If the the buffer.data != nullptr
check indicates that the buffer was null, then
relying on the value in buffer_size is no longer
safe. The later call to uv_pipe_getpeername
depends on the buffer_size being correct to
avoid deferencing buffer.data if it is not
big enough.

Signed-off-by: Michael Dawson <mdawson@devrus.com>

PR-URL: nodejs#42663
Reviewed-By: Darshan Sen <raisinten@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

src/node_report_utils.cc

@@ -95,6 +95,8 @@ static void ReportPipeEndpoints(uv_handle_t* h, JSONWriter* writer) {
     buffer = MallocedBuffer<char>(buffer_size);
     if (buffer.data != nullptr) {
       rc = uv_pipe_getsockname(&handle->pipe, buffer.data, &buffer_size);
+    } else {
+      buffer_size = 0;
     }
   }
   if (rc == 0 && buffer_size != 0 && buffer.data != nullptr) {