出现这个错误了，这咋改呢？
Sphinx 2.3.2-id64-beta (4409612)
Copyright (c) 2001-2016, Andrew Aksyonoff
Copyright (c) 2008-2016, Sphinx Technologies Inc (http://sphinxsearch.com)
using config file 'sphinx.conf'...
indexing index 'hash'...
(node:1494) [MONGODB DRIVER] Warning: Current Server Discovery and Monitoring engine is deprecated, and will be removed in a future version. To use the new Server Discover and Monitoring engine, pass option { useUnifiedTopology: true } to the MongoClient constructor.
(Use node --trace-warnings ... to show where the warning was created)
collected 123 docs, 0.0 MB
sorted 0.0 Mhits, 100.0% done
total 123 docs, 6168 bytes
total 0.332 sec, 18545 bytes/sec, 369.83 docs/sec
WARNING: no such index 'searchd', skipping.
total 4 reads, 0.000 sec, 12.9 kb/call avg, 0.0 msec/call avg
total 12 writes, 0.000 sec, 2.8 kb/call avg, 0.0 msec/call avg