Prevent extinction with empty zerolag pdfs

gstlal-inspiral/bin/gstlal_inspiral_marginalize_likelihoods_online

@@ -256,10 +256,18 @@ def main():
 				# get the zerolag pdf for this bin and use it to perform bin-specific extinction
 				zerolag_counts_url = url_from_registry(reg, zerolag_counts_path)
 				pdf += far.RankingStatPDF.from_xml(ligolw_utils.load_url(zerolag_counts_url, verbose = options.verbose, contenthandler = far.RankingStat.LIGOLWContentHandler), u"gstlal_inspiral_likelihood")
-				if data:
-					data += pdf.new_with_extinction()
+				if len(numpy.nonzero(pdf.zero_lag_lr_lnpdf.array)[0]) > 0:
+					# LR calculation has started and we are ready to perform first-round extinction
+					if data:
+						data += pdf.new_with_extinction()
+					else:
+						data = pdf.new_with_extinction()
 				else:
-					data = pdf.new_with_extinction()
+					logging.warning(f'Skipping first-round extinction for {}')
+					if data:
+						data += pdf
+					else:
+						data = pdf
 
 			# while looping through registries
 			# send heartbeat messages