Prevent Nan-weights from being accumulated

NEWS.rst

@@ -1,6 +1,8 @@
 New in 0.5:
 ===========
 
+- fixed a bug that caused NaNs to slip through to the integrated result if they
+  were coming from the point's weight
 - it is now possible to disable channels by setting their weight to zero
 - the function ``multi_channel_verbose_callback`` now prints an overview of the
   smallest and largest a-priori weights

include/hep/mc/internal/accumulator.hpp

@@ -75,17 +75,18 @@ class accumulator<T, true>
 		// are generated here
 		T value = integrand.function()(point, projector);
 
-		if (std::isfinite(value))
+		if (value != T())
 		{
-			if (value != T())
+			value *= point.weight();
+
+			if (std::isfinite(value))
 			{
-				value *= point.weight();
 				accumulate(sums_[0], sums_[1], compensations_[0], value);
 			}
-		}
-		else
-		{
-			value = T();
+			else
+			{
+				value = T();
+			}
 		}
 
 		return value;
@@ -198,17 +199,18 @@ class accumulator<T, false>
 		// are generated here
 		T value = integrand.function()(point);
 
-		if (std::isfinite(value))
+		if (value != T())
 		{
-			if (value != T())
+			value *= point.weight();
+
+			if (std::isfinite(value))
 			{
-				value *= point.weight();
 				accumulate(sums_[0], sums_[1], sums_[2], value);
 			}
-		}
-		else
-		{
-			value = T();
+			else
+			{
+				value = T();
+			}
 		}
 
 		return value;