From 978143ce99a2db9da7bf5a7d46e9f7a3e9ad1e58 Mon Sep 17 00:00:00 2001
From: Thomas Pelletier <pelletier.thomas@gmail.com>
Date: Fri, 19 Feb 2021 08:53:19 -0500
Subject: [PATCH] Ensure that slices have been allocated when entering array

---
 internal/reflectbuild/reflectbuild.go | 15 +++++++++++++++
 unmarshal.go                          |  4 ++++
 2 files changed, 19 insertions(+)

diff --git a/internal/reflectbuild/reflectbuild.go b/internal/reflectbuild/reflectbuild.go
index d2ce732..4a67797 100644
--- a/internal/reflectbuild/reflectbuild.go
+++ b/internal/reflectbuild/reflectbuild.go
@@ -490,6 +490,21 @@ func (b *Builder) Set(v reflect.Value) error {
 	return t.set(v)
 }
 
+// EnsureSlice makes sure that the cursor points to a non-nil slice.
+func (b *Builder) EnsureSlice() error {
+	t := b.top()
+	v := t.get()
+	if v.Kind() != reflect.Slice {
+		return IncorrectKindError{Actual: v.Kind(), Expected: reflect.Slice}
+	}
+
+	if v.IsNil() {
+		v.Set(reflect.MakeSlice(v.Type(), 0, 0))
+	}
+
+	return nil
+}
+
 func checkKindInt(rt reflect.Type) error {
 	switch rt.Kind() {
 	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
diff --git a/unmarshal.go b/unmarshal.go
index 43f8a94..3dd4559 100644
--- a/unmarshal.go
+++ b/unmarshal.go
@@ -65,6 +65,10 @@ func (u *unmarshaler) ArrayBegin() {
 		return
 	}
 	u.builder.Save()
+	u.err = u.builder.EnsureSlice()
+	if u.err != nil {
+		return
+	}
 	if u.assign {
 		u.assign = false
 	} else {