HLS Segmenter: Don't error if dumpMap or snapshot are called early
HLS Segmenter: Don't error if dumpMap or snapshot are called early

* If we don't yet have a finalizer (we think we're still loading, or no data
  has come in yet), return null instead of erroring

StreamMachine/StreamMachine,pedropapa/StreamMachine,SCPR/StreamMachine,DreamNetwork/StreamMachine,StreamMachine/StreamMachine,pteich/StreamMachine,SCPR/StreamMachine,cdgraff/StreamMachine,DreamNetwork/StreamMachine,pedropapa/StreamMachine,cdgraff/StreamMachine,pteich/StreamMachine