Fix overlap calculation when geneset is empty. Fixes #397

Author: mikekucera

EnrichmentMapPlugin/src/main/java/org/baderlab/csplugins/enrichmentmap/task/ComputeSimilarityTaskParallel.java

@@ -149,6 +149,9 @@ static GenesetSimilarity computeGenesetSimilarity(EMCreationParameters params, S
 
 		double coeffecient = computeSimilarityCoeffecient(params, intersection, union, geneset1, geneset2);
 
+		if(!Double.isFinite(coeffecient))
+			return null;
+		
 		if(coeffecient < params.getSimilarityCutoff())
 			return null;