leak-795988: Tidy up NodeType empty node list
leak-795988: Tidy up NodeType empty node list

Potential leak from storing data for longer than we should.

Signed-off-by: Joe Walker <7a17872fbb32c7d760c9a16ee3076daead11efcf@mozilla.com>

mozilla/gcli,joewalker/gcli,mozilla/gcli,joewalker/gcli,mozilla/gcli