fix add null-check to avoid NPE for issue #1882

core/src/main/java/com/alibaba/fastjson2/reader/ObjectReaderCreator.java

@@ -684,6 +684,7 @@ public class ObjectReaderCreator {
 
         boolean[] flags = null;
         int maskCount = 0;
+        if (setterFieldReaders != null) {
             for (int i = 0; i < setterFieldReaders.length; i++) {
                 FieldReader setterFieldReader = setterFieldReaders[i];
                 if (fieldReaders.containsKey(setterFieldReader.fieldName)) {
@@ -704,6 +705,7 @@ public class ObjectReaderCreator {
                 }
                 setterFieldReaders = array;
             }
+        }
 
         return (ObjectReader<T>) new ObjectReaderNoneDefaultConstructor(
                 objectClass,

core/src/main/java/com/alibaba/fastjson2/reader/ObjectReaderException.java

@@ -341,6 +341,15 @@ final class ObjectReaderException<T>
         return (T) object;
     }
 
+    @Override
+    public T createInstance(Map map, long features) {
+        if (map == null) {
+            return null;
+        }
+
+        return readObject(JSONReader.of(JSON.toJSONString(map)), features);
+    }
+
     @Override
     public T readJSONBObject(JSONReader jsonReader, Type fieldType, Object fieldName, long features) {
         if (jsonReader.getType() == JSONB.Constants.BC_TYPED_ANY) {

core/src/main/java/com/alibaba/fastjson2/reader/ObjectReaderNoneDefaultConstructor.java

@@ -471,6 +471,7 @@ public class ObjectReaderNoneDefaultConstructor<T>
                         : valueMap
         );
 
+        if (setterFieldReaders != null) {
             for (int i = 0; i < setterFieldReaders.length; i++) {
                 FieldReader fieldReader = setterFieldReaders[i];
                 Object fieldValue = map.get(fieldReader.fieldName);
@@ -495,6 +496,7 @@ public class ObjectReaderNoneDefaultConstructor<T>
 
                 fieldReader.accept(object, fieldValue);
             }
+        }
 
         return object;
     }

core/src/test/java/com/alibaba/fastjson2/issues_1800/Issue1822.java

@@ -0,0 +1,54 @@
+package com.alibaba.fastjson2.issues_1800;
+
+import com.alibaba.fastjson2.JSON;
+import com.alibaba.fastjson2.JSONObject;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+public class Issue1822 {
+    private static String JSON_STRING;
+    private static MyObj MY_OBJ;
+
+    @BeforeAll
+    public static void init() {
+        MY_OBJ = new MyObj();
+        MY_OBJ.setThrowable(new Throwable("测试"));
+        JSON_STRING = JSON.toJSONString(MY_OBJ);
+    }
+
+    @Test
+    void testWithError() {
+        JSONObject jsonObject = JSONObject.parseObject(JSON_STRING);
+        MyObj myObj = jsonObject.toJavaObject(MyObj.class);
+        assertEquals(JSON_STRING, JSON.toJSONString(myObj));
+        assertEquals(MY_OBJ.toString(), myObj.toString());
+    }
+
+    @Test
+    void testWithoutError() {
+        MyObj myObj = JSONObject.parseObject(JSON_STRING, MyObj.class);
+        assertEquals(JSON_STRING, JSON.toJSONString(myObj));
+        assertEquals(MY_OBJ.toString(), myObj.toString());
+    }
+
+    private static class MyObj {
+        private Throwable throwable;
+
+        public Throwable getThrowable() {
+            return throwable;
+        }
+
+        public void setThrowable(Throwable throwable) {
+            this.throwable = throwable;
+        }
+
+        @Override
+        public String toString() {
+            return "MyObj{" +
+                    "throwable=" + throwable +
+                    '}';
+        }
+    }
+}

safemode-test/src/test/java/com/alibaba/fastjson2/SafeModeTest.java

@@ -6,6 +6,7 @@ import java.io.IOException;
 import java.util.Map;
 
 import static org.junit.jupiter.api.Assertions.*;
+import static org.junit.jupiter.api.Assertions.assertEquals;
 
 public class SafeModeTest {
     @Test
@@ -27,9 +28,6 @@ public class SafeModeTest {
         Throwable e1 = JSON.parseObject(jsonString, Throwable.class);
         assertEquals(Throwable.class, e1.getClass());
         JSONObject object = JSON.parseObject(jsonString);
-        assertThrows(
+        assertEquals(Throwable.class, object.toJavaObject(Throwable.class).getClass());
-                Exception.class,
-                () -> object.toJavaObject(Throwable.class)
-        );
     }
 }