DevTools: Gracefully ignore unknown variable scopes.

Source/bindings/core/v8/DebuggerScript.js

 /*
  * Copyright (C) 2010 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 59 matching lines @@
 
 DebuggerScript.getFunctionScopes = function(fun)
 {
     var mirror = MakeMirror(fun);
     var count = mirror.scopeCount();
     if (count == 0)
         return null;
     var result = [];
     for (var i = 0; i < count; i++) {
         var scopeDetails = mirror.scope(i).details();
-        result[i] = {
+        var scopeObject = DebuggerScript._buildScopeObject(scopeDetails.type(), scopeDetails.object());
+        if (!scopeObject)
+            continue;
+        result.push({
             type: scopeDetails.type(),
-            object: DebuggerScript._buildScopeObject(scopeDetails.type(), scopeDetails.object())
-        };
+            object: scopeObject
+        });
     }
     return result;
 }
 
 DebuggerScript.getCollectionEntries = function(object)
 {
     var mirror = MakeMirror(object, true /* transient */);
     if (mirror.isMap())
         return mirror.entries();
     if (mirror.isSet() || mirror.isIterator()) {
@@ skipping 281 matching lines @@
 
     // Calculated lazily.
     var scopeChain;
     var funcMirror;
     var location;
 
     function lazyScopeChain()
     {
         if (!scopeChain) {
             scopeChain = [];
-            for (var i = 0; i < scopeObjects.length; ++i)
-                scopeChain.push(DebuggerScript._buildScopeObject(scopeTypes[i], scopeObjects[i]));
+            for (var i = 0, j = 0; i < scopeObjects.length; ++i) {
+                var scopeObject = DebuggerScript._buildScopeObject(scopeTypes[i], scopeObjects[i]);
+                if (scopeObject) {
+                    scopeTypes[j] = scopeTypes[i];
+                    scopeChain[j] = scopeObject;
+                    ++j;
+                }
+            }
+            scopeTypes.length = scopeChain.length;
             scopeObjects = null; // Free for GC.
         }
         return scopeChain;
     }
 
+    function lazyScopeTypes()
+    {
+        if (!scopeChain)
+            lazyScopeChain();
+        return scopeTypes;
+    }
+
     function ensureFuncMirror()
     {
         if (!funcMirror) {
             funcMirror = MakeMirror(funcObject);
             if (!funcMirror.isFunction())
                 funcMirror = new UnresolvedFunctionMirror(funcObject);
         }
         return funcMirror;
     }
 
@@ skipping 81 matching lines @@
     }
 
     return {
         "sourceID": sourceID,
         "line": line,
         "column": column,
         "scriptName": scriptName,
         "functionName": functionName,
         "thisObject": thisObject,
         "scopeChain": lazyScopeChain,
-        "scopeType": scopeTypes,
+        "scopeType": lazyScopeTypes,
         "evaluate": evaluate,
         "caller": callerFrame,
         "restart": restart,
         "setVariableValue": setVariableValue,
         "stepInPositions": stepInPositions,
         "isAtReturn": isAtReturn,
         "returnValue": returnValue
     };
 }
 
@@ skipping 35 matching lines @@
         "parentPromise": eventData.parentPromise().value(),
         "status": eventData.status()
     };
 }
 
 // We never resolve Mirror by its handle so to avoid memory leaks caused by Mirrors in the cache we disable it.
 ToggleMirrorCache(false);
 
 return DebuggerScript;
 })();