Handling exception while GetJSONObject in script debugger.

During GetChildren phase when we try to build JSON object we might throw exception. That skipped calling .Detach on the AutoPtr - which leads to release
the debugger property again.
Fixed that by catching and discarding the exception.

Author: akroshg

lib/Jsrt/JsrtDebuggerObject.cpp

@@ -85,15 +85,22 @@ Js::DynamicObject * JsrtDebuggerObjectBase::GetChildren(WeakArenaReference<Js::I
                 if (resolvedObjectDisplay != nullptr)
                 {
                     JsrtDebuggerObjectBase* debuggerObject = JsrtDebuggerObjectProperty::Make(this->GetDebuggerObjectsManager(), objectDisplayWeakRef);
-                    Js::DynamicObject* object = debuggerObject->GetJSONObject(resolvedObject.scriptContext, /* forceSetValueProp */ false);
-                    Js::Var marshaledObj = Js::CrossSite::MarshalVar(scriptContext, object);
-                    if (resolvedObjectDisplay->IsFake())
+                    try
                     {
-                        Js::JavascriptOperators::OP_SetElementI((Js::Var)debuggerOnlyPropertiesArray, Js::JavascriptNumber::ToVar(debuggerOnlyPropertiesArrayCount++, scriptContext), marshaledObj, scriptContext);
+                        Js::DynamicObject* object = debuggerObject->GetJSONObject(resolvedObject.scriptContext, /* forceSetValueProp */ false);
+                        Js::Var marshaledObj = Js::CrossSite::MarshalVar(scriptContext, object);
+                        if (resolvedObjectDisplay->IsFake())
+                        {
+                            Js::JavascriptOperators::OP_SetElementI((Js::Var)debuggerOnlyPropertiesArray, Js::JavascriptNumber::ToVar(debuggerOnlyPropertiesArrayCount++, scriptContext), marshaledObj, scriptContext);
+                        }
+                        else
+                        {
+                            Js::JavascriptOperators::OP_SetElementI((Js::Var)propertiesArray, Js::JavascriptNumber::ToVar(propertiesArrayCount++, scriptContext), marshaledObj, scriptContext);
+                        }
                     }
-                    else
+                    catch (const Js::JavascriptException& err)
                     {
-                        Js::JavascriptOperators::OP_SetElementI((Js::Var)propertiesArray, Js::JavascriptNumber::ToVar(propertiesArrayCount++, scriptContext), marshaledObj, scriptContext);
+                        err.GetAndClear();   // discard exception object
                     }
                     objectDisplayWeakRef->ReleaseStrongReference();
                     objectDisplayWeakRef.Detach();
@@ -415,11 +422,18 @@ Js::DynamicObject * JsrtDebuggerStackFrame::GetLocalsObject(Js::ScriptContext* s
                     {
                         AutoPtr<WeakArenaReference<Js::IDiagObjectModelDisplay>> objectDisplayWeakRef(resolvedObject.GetObjectDisplay());
                         JsrtDebuggerObjectBase* debuggerObject = JsrtDebuggerObjectScope::Make(debuggerObjectsManager, objectDisplayWeakRef, scopesCount);
-                        Js::DynamicObject* object = debuggerObject->GetJSONObject(resolvedObject.scriptContext, /* forceSetValueProp */ false);
-                        Assert(object != nullptr);
-                        Js::Var marshaledObj = Js::CrossSite::MarshalVar(scriptContext, object);
-                        Js::JavascriptOperators::OP_SetElementI((Js::Var)scopesArray, Js::JavascriptNumber::ToVar(scopesCount, scriptContext), marshaledObj, scriptContext);
-                        scopesCount++;
+                        try
+                        {
+                            Js::DynamicObject* object = debuggerObject->GetJSONObject(resolvedObject.scriptContext, /* forceSetValueProp */ false);
+                            Assert(object != nullptr);
+                            Js::Var marshaledObj = Js::CrossSite::MarshalVar(scriptContext, object);
+                            Js::JavascriptOperators::OP_SetElementI((Js::Var)scopesArray, Js::JavascriptNumber::ToVar(scopesCount, scriptContext), marshaledObj, scriptContext);
+                            scopesCount++;
+                        }
+                        catch (const Js::JavascriptException& err)
+                        {
+                            err.GetAndClear();   // discard exception object
+                        }
                         objectDisplayWeakRef.Detach();
                     }
                 }

test/Debugger/exceptionWhileFetchingProp.js

@@ -0,0 +1,18 @@
+//-------------------------------------------------------------------------------------------------------
+// Copyright (C) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE.txt file in the project root for full license information.
+//-------------------------------------------------------------------------------------------------------
+
+var p = new Proxy({x:10}, {
+    getOwnPropertyDescriptor: function (oTarget, sKey) {
+        throw new Error('');
+        return { configurable: true, enumerable: true, value: 5 };
+    }
+  });
+  
+  function f() {
+    var j = 1; /**bp:evaluate('p',1);**/
+  }
+  f();
+  print('Pass');
+  

test/Debugger/exceptionWhileFetchingProp.js.dbg.baseline

@@ -0,0 +1,10 @@
+[
+  {
+    "evaluate": {
+      "p": {
+        "#__proto__": "Object {...}",
+        "[Proxy]": "Proxy {...}"
+      }
+    }
+  }
+]

test/Debugger/rlexe.xml

@@ -114,4 +114,10 @@
       <files>loadscript_after_detach.js</files>
     </default>
   </test>
+  <test>
+    <default>
+      <compile-flags>-debuglaunch -dbgbaseline:exceptionWhileFetchingProp.js.dbg.baseline</compile-flags>
+      <files>exceptionWhileFetchingProp.js</files>
+    </default>
+  </test>
 </regress-exe>