From 7d15fc2f2624e2aa871aaf656e4654aeea2bb116 Mon Sep 17 00:00:00 2001
From: Seebs <seebs@seebs.net>
Date: Fri, 26 Feb 2021 14:26:02 -0600
Subject: [PATCH] don't reduce errors with non-errors

if we got an error, we don't have to merge it. so either ctx.Err or
resp.err being non-nil means we shouldn't be reducing, but we still need
to grab the responses to make sure we waited for them all.
---
 executor.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/executor.go b/executor.go
index 7add7487c..1b3848916 100644
--- a/executor.go
+++ b/executor.go
@@ -5786,7 +5786,7 @@ func (e *executor) mapperLocal(ctx context.Context, shards []uint64, mapFn mapFu
 		if resp.err != nil && err == nil {
 			err = resp.err
 		}
-		if ctx.Err() == nil {
+		if resp.err == nil && ctx.Err() == nil {
 			// Only useful to do a possibly-expensive
 			// reduce if we don't already know we don't
 			// need it.