Fix panic on assigning empty array to non-slice or array

See jackc/pgx#881

Author: jackc

aclitem_array.go

@@ -5,6 +5,7 @@ import (
 	"testing"
 
 	"github.com/jackc/pgtype"
+	"github.com/stretchr/testify/require"
 )
 
 func TestParseUntypedTextArray(t *testing.T) {
@@ -113,3 +114,14 @@ func TestParseUntypedTextArray(t *testing.T) {
 		}
 	}
 }
+
+// https://github.com/jackc/pgx/issues/881
+func TestArrayAssignToEmptyToNonSlice(t *testing.T) {
+	var a pgtype.Int4Array
+	err := a.Set([]int32{})
+	require.NoError(t, err)
+
+	var iface interface{}
+	err = a.AssignTo(&iface)
+	require.EqualError(t, err, "cannot assign *pgtype.Int4Array to *interface {}")
+}