From 71c6527c9174115174af104c2483ff2588cdc934 Mon Sep 17 00:00:00 2001
From: Pepijn de Vos <pepijn.devos@juliacomputing.com>
Date: Mon, 2 Oct 2023 14:08:04 +0200
Subject: [PATCH] handle different stats types, including nothing

---
 src/ensemble/basic_ensemble_solve.jl | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/src/ensemble/basic_ensemble_solve.jl b/src/ensemble/basic_ensemble_solve.jl
index a6da51f81..8db2f5065 100644
--- a/src/ensemble/basic_ensemble_solve.jl
+++ b/src/ensemble/basic_ensemble_solve.jl
@@ -24,7 +24,17 @@ $(TYPEDEF)
 struct EnsembleSerial <: BasicEnsembleAlgorithm end
 
 function merge_stats(us)
-    mapreduce(x -> x.stats, merge, us)
+    st = Iterators.filter(!isnothing, (x.stats for x in us))
+    try
+        return reduce(merge, st)
+    catch e
+        if isa(e, MethodError)
+            # there were no stats or they didn't have a merge method
+            return nothing
+        else
+            rethrow(e)
+        end
+    end
 end
 
 function __solve(prob::AbstractEnsembleProblem,