From 4418d4575a419bfb9a44250c8f2320f24b6c43b5 Mon Sep 17 00:00:00 2001
From: Dmitry Panov <dop@itoolabs.com>
Date: Mon, 16 May 2022 13:39:00 +0100
Subject: [PATCH] Do not use fmt.Sprintf() for plain error strings. Fixes #388.

---
 runtime.go      | 7 ++++++-
 runtime_test.go | 9 +++++++++
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/runtime.go b/runtime.go
index eace4d61..5ba15ba0 100644
--- a/runtime.go
+++ b/runtime.go
@@ -470,7 +470,12 @@ func (r *Runtime) typeErrorResult(throw bool, args ...interface{}) {
 }
 
 func (r *Runtime) newError(typ *Object, format string, args ...interface{}) Value {
-	msg := fmt.Sprintf(format, args...)
+	var msg string
+	if len(args) > 0 {
+		msg = fmt.Sprintf(format, args...)
+	} else {
+		msg = format
+	}
 	return r.builtin_new(typ, []Value{newStringValue(msg)})
 }
 
diff --git a/runtime_test.go b/runtime_test.go
index 29bd293c..03dfdceb 100644
--- a/runtime_test.go
+++ b/runtime_test.go
@@ -2375,6 +2375,15 @@ func TestErrorStack(t *testing.T) {
 	testScript(SCRIPT, _undefined, t)
 }
 
+func TestErrorFormatSymbols(t *testing.T) {
+	vm := New()
+	vm.Set("a", func() (Value, error) { return nil, errors.New("something %s %f") })
+	_, err := vm.RunString("a()")
+	if !strings.Contains(err.Error(), "something %s %f") {
+		t.Fatalf("Wrong value %q", err.Error())
+	}
+}
+
 /*
 func TestArrayConcatSparse(t *testing.T) {
 function foo(a,b,c)