fix:(ast) checkRaw() check if node is nil pointer first (#250)

ast/node.go

@@ -156,12 +156,12 @@ func (self *Node) Raw() (string, error) {
 }
 
 func (self *Node) checkRaw() error {
-    if self.IsRaw() {
-        self.parseRaw(false)
-    }
     if err := self.Check(); err != nil {
         return err
     }
+    if self.IsRaw() {
+        self.parseRaw(false)
+    }
     return nil
 }
 

issue_test/issue248_test.go

@@ -0,0 +1,35 @@
+/*
+ * Copyright 2021 ByteDance Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package issue_test
+
+import (
+    `testing`
+
+    `github.com/bytedance/sonic`
+    `github.com/stretchr/testify/require`
+)
+
+func TestIssue248(t *testing.T) {
+    var d = `{}`
+    n, err := sonic.GetFromString(d)
+    require.Nil(t, err)
+    v := n.GetByPath("a", 0)
+    require.Nil(t, v)
+    s, err := v.Get("a").Index(0).String()
+    require.NotNil(t, err)
+    require.Equal(t, "", s)
+}