getGeneHood fails when passed undefined

```
Uncaught TypeError: geneHood.splice is not a function
at IncomingMessage.res.on (node_modules/node-mist3/src/Genes.js:110:16)
      at endReadableNT (_stream_readable.js:974:12)
      at _combinedTickCallback (internal/process/next_tick.js:74:11)
      at process._tickCallback (internal/process/next_tick.js:98:9)
```