fixes issue with method when no comparators are given

app/src/main/java/net/pokeranalytics/android/calculus/Calculator.kt

@@ -73,11 +73,17 @@ class Calculator {
 				allConditions.addAll(conditions)
 				allConditions.addAll(comparatorConditions)
 
-				val group = ComputableGroup(allConditions.name(), conditions)
+				val group = ComputableGroup(allConditions.name(), allConditions)
 				computableGroups.add(group)
 
 			}
-			return Calculator.computeGroups(realm, computableGroups, options)
+
+			if (computableGroups.size == 0) {
+				val group = ComputableGroup(conditions.name(), conditions)
+				computableGroups.add(group)
+			}
+
+			return this.computeGroups(realm, computableGroups, options)
 		}
 
 		fun computeStatsWithFilters(realm: Realm, filters: List<Filter>, options: Options): Report {