diff --git a/examples/dummy_error/conf.toml b/examples/dummy_error/conf.toml
new file mode 100644
index 0000000..72576e5
--- /dev/null
+++ b/examples/dummy_error/conf.toml
@@ -0,0 +1,27 @@
+[[stages]]
+name = "dummy"
+[stages.executor]
+name = "sandbox"
+[stages.executor.with.default]
+args = ["./dummy", "--score", "-1"]
+env = ["PATH=/usr/bin:/bin"]
+cpuLimit = 10_000_000_000
+memoryLimit = 104_857_600
+procLimit = 50
+copyInCwd = true
+[stages.executor.with.default.copyIn.dummy]
+src = "./../../build/dummy"
+copyOut = ["stdout", "stderr"]
+[stages.executor.with.default.stdin]
+content = ""
+[stages.executor.with.default.stdout]
+name = "stdout"
+max = 4_096
+[stages.executor.with.default.stderr]
+name = "stderr"
+max = 4_096
+[stages.parser]
+name = "dummy"
+[stages.parser.with]
+score = 10
+comment = " + comment from toml conf"
diff --git a/examples/dummy_error/run.sh b/examples/dummy_error/run.sh
new file mode 100755
index 0000000..9088452
--- /dev/null
+++ b/examples/dummy_error/run.sh
@@ -0,0 +1,10 @@
+#!/usr/bin/env bash
+
+set -xe
+DIRNAME=`dirname -- "$0"`
+# cd to make CopyInCwd work
+cd $DIRNAME
+./../../build/joj3
+cat ./joj3_result.json
+rm -f ./joj3_result.json
+cd -
diff --git a/pkg/dummy/dummy.go b/pkg/dummy/dummy.go
index 1248dd7..938a7f4 100644
--- a/pkg/dummy/dummy.go
+++ b/pkg/dummy/dummy.go
@@ -2,7 +2,6 @@ package dummy
 
 import (
 	"fmt"
-	"log/slog"
 )
 
 type Conf struct {
@@ -16,7 +15,10 @@ type Result struct {
 
 func Run(conf Conf) (res Result, err error) {
 	if conf.Score < 0 {
-		slog.Error("dummy negative score", "score", conf.Score)
+		// Just return the error here instead of logging, as it is run inside
+		// the sandbox, the logs will not show in drone output directly.
+		// If there are more kinds of errors need to be handled separately, add
+		// more fields in the Result struct, don't mess everything up in Stderr.
 		err = fmt.Errorf("dummy negative score: %d", conf.Score)
 		return
 	}