升级Jint至3.0.1后触发空引用异常，求排查解决方法

问题概述 #

原本在Jint 3.0.0-beta-2033中正常运行的脚本，升级至3.0.1及最新正式版后执行时抛出Object reference not set to an instance of an object异常，已尝试替换脚本空值但无效。

涉事脚本代码 #

(function () {
var callResult;
var flowHelper = require('flowHelper');
  var serverScriptExecutionContext = flowHelper.getServerScriptExecutionContext(context,request,args,readConfig,result,log,flowHelper);
var Fields = args.Fields;
var fieldsDataForSave = flowHelper.getValidatedPageDataForLoanCalculation(serverScriptExecutionContext);
      log.LogDebug('Calculate Loan Conditions Action fieldsDataForSave: ' + JSON.stringify(fieldsDataForSave));
callResult = JSON.parse(__remote_call__(context.nodes.loans, 'SaveFields', __jsonify__({"appId": context.AppId, "fields": fieldsDataForSave})));
}());

完整错误日志 #

Method CalculateLoanConditions has thrown an exception.
System.NullReferenceException: Object reference not set to an instance of an object.
at Jint.Runtime.Interpreter.Expressions.JintExpression.GetValue(EvaluationContext context)
at Jint.EsprimaExtensions.TryGetKey[T](T expression, Engine engine, Boolean resolveComputed)
at Jint.Runtime.Interpreter.Expressions.JintObjectExpression.BuildObjectNormal(EvaluationContext context)
at Jint.Runtime.Interpreter.Expressions.JintExpression.GetValue(EvaluationContext context)
at Jint.Runtime.Interpreter.Expressions.JintCallExpression.ArgumentListEvaluation(EvaluationContext context)
at Jint.Runtime.Interpreter.Expressions.JintCallExpression.EvaluateInternal(EvaluationContext context)
at Jint.Runtime.Interpreter.Expressions.JintExpression.GetValue(EvaluationContext context)
at Jint.Runtime.Interpreter.Statements.JintReturnStatement.ExecuteInternal(EvaluationContext context)
at Jint.Native.Function.ScriptFunction.Call(JsValue thisObject, JsValue[] arguments)
at Jint.Runtime.Interpreter.Expressions.JintCallExpression.EvaluateInternal(EvaluationContext context)
at Jint.Runtime.Interpreter.Expressions.JintExpression.GetValue(EvaluationContext context)
at Jint.Runtime.Interpreter.Statements.JintReturnStatement.ExecuteInternal(EvaluationContext context)
at Jint.Native.Function.ScriptFunction.Call(JsValue thisObject, JsValue[] arguments)
at Jint.Runtime.Interpreter.Expressions.JintCallExpression.EvaluateInternal(EvaluationContext context)
at Jint.Runtime.Interpreter.Expressions.JintExpression.GetValue(EvaluationContext context)
at Jint.Runtime.Interpreter.Statements.JintVariableDeclaration.ExecuteInternal(EvaluationContext context)
at Jint.Native.Function.ScriptFunction.Call(JsValue thisObject, JsValue[] arguments)
at Jint.Runtime.Interpreter.Expressions.JintCallExpression.EvaluateInternal(EvaluationContext context)
at Jint.Runtime.Interpreter.Expressions.JintExpression.GetValue(EvaluationContext context)
at Jint.Runtime.Interpreter.Statements.JintVariableDeclaration.ExecuteInternal(EvaluationContext context)
at Jint.Native.Function.ScriptFunction.Call(JsValue thisObject, JsValue[] arguments)
at Jint.Runtime.Interpreter.Expressions.JintCallExpression.EvaluateInternal(EvaluationContext context)
at Jint.Runtime.Interpreter.Expressions.JintExpression.GetValue(EvaluationContext context)
at Jint.Runtime.Interpreter.Expressions.JintAssignmentExpression.SimpleAssignmentExpression.AssignToIdentifier(EvaluationContext context, JintIdentifierExpression left, JintExpression right, Boolean hasEvalOrArguments)
at Jint.Runtime.Interpreter.Statements.JintVariableDeclaration.ExecuteInternal(EvaluationContext context)
at Jint.Native.Function.ScriptFunction.Call(JsValue thisObject, JsValue[] arguments)
at Jint.Runtime.Interpreter.Expressions.JintCallExpression.EvaluateInternal(EvaluationContext context)
at Jint.Runtime.Interpreter.Expressions.JintExpression.GetValue(EvaluationContext context)
at Jint.Runtime.Interpreter.Statements.JintExpressionStatement.ExecuteInternal(EvaluationContext context)
at Jint.Engine.ScriptEvaluation(ScriptRecord scriptRecord)
at Jint.Engine.ExecuteWithConstraints[T](Boolean strict, Func`1 callback) at Jint.Engine.Execute(Script script) at Jint.Engine.Evaluate(String code) at Lending.FrozenFlow.Core.DSL.Misc.ScriptFlow.ExecuteScriptOptimisticallyAndGetNextPage(ExecutionContext`1 result, String script) in C:\ML\as.accessdigital.lending.shared.babbler.nodes\AS.Lending.FrozenFlow.Core\DSL\Misc\ScriptFlow.cs:line 173
at Lending.FrozenFlow.Core.DSL.Misc.ScriptFlow.<>c__DisplayClass19_0.b__0(ExecutionContext`1 result) in C:\ML\as.accessdigital.lending.shared.babbler.nodes\AS.Lending.FrozenFlow.Core\DSL\Misc\ScriptFlow.cs:line 201

根本原因分析 #

从错误栈来看，异常发生在JintObjectExpression.BuildObjectNormal方法中，说明Jint在解析脚本中的对象字面量{"appId": context.AppId, "fields": fieldsDataForSave}时出现空引用。结合版本差异，大概率是Jint 3.0.1之后对对象字面量中null值的处理逻辑发生了变化，或者自定义的__jsonify__函数在新版本Jint下无法正确处理null类型的JsValue，导致.NET端出现空引用。

解决方法 #

1. 提前检查关键变量是否为null
   在调用__jsonify__前添加变量校验，避免传入null值触发异常：

   // 校验关键变量
   if (context.AppId === null || context.AppId === undefined) {
       log.LogError('context.AppId is missing or null');
       return;
   }
   if (fieldsDataForSave === null || fieldsDataForSave === undefined) {
       log.LogError('fieldsDataForSave is missing or null');
       return;
   }
   // 执行远程调用
   callResult = JSON.parse(__remote_call__(context.nodes.loans, 'SaveFields', __jsonify__({"appId": context.AppId, "fields": fieldsDataForSave})));
   

2. 分步构建对象替代字面量
   绕过Jint对对象字面量的直接解析，改用分步赋值的方式创建参数对象：

   var params = {};
   params.appId = context.AppId ?? null;
   params.fields = fieldsDataForSave ?? null;
   callResult = JSON.parse(__remote_call__(context.nodes.loans, 'SaveFields', __jsonify__(params)));
   

3. 排查自定义__jsonify__函数的兼容性
   如果__jsonify__是你方实现的.NET扩展函数，检查其处理JsValue的逻辑：

   • 确保在处理JsValue为JsNull或JsUndefined时不会直接调用null对象的方法
   • 适配Jint 3.0.1及以上版本中JsValue的类型判断逻辑（比如新版本中IsNull和IsUndefined的判断方式是否有变化）

4. 检查Jint引擎配置
   确认升级后是否开启了严格模式或其他行为变更的配置，若有尝试关闭：

   var engine = new Engine(options =>
   {
       // 若开启了严格模式，尝试注释掉
       // options.SetStrictMode(true);
   });
   

内容的提问来源于stack exchange，提问作者user24343590