Add handling of empty stack in the backtrace debug request....

src/debug-delay.js

 // Copyright 2006-2008 the V8 project authors. 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
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 814 matching lines @@
 ExceptionEvent.prototype.executionState = function() {
   return this.exec_state_;
 };
 
 
 ExceptionEvent.prototype.eventType = function() {
   return Debug.DebugEvent.Exception;
 };
 
 
+ExceptionEvent.prototype.exception = function() {
+  return this.exception_;
+}
+
+
 ExceptionEvent.prototype.uncaught = function() {
   return this.uncaught_;
 }
 
+
 ExceptionEvent.prototype.func = function() {
   return this.exec_state_.frame(0).func();
 };
 
 
 ExceptionEvent.prototype.sourceLine = function() {
   return this.exec_state_.frame(0).sourceLine();
 };
 
 
@@ skipping 466 matching lines @@
 
   // Clear break point.
   Debug.clearBreakPoint(break_point);
 }
 
 
 DebugCommandProcessor.prototype.backtraceRequest_ = function(request, response) {
   // Get the number of frames.
   var total_frames = this.exec_state_.frameCount();
 
+  // Create simple response if there are no frames.
+  if (total_frames == 0) {
+    response.body = {
+      totalFrames: total_frames
+    }
+    return;
+  }
+
   // Default frame range to include in backtrace.
   var from_index = 0
   var to_index = kDefaultBacktraceLength;
 
   // Get the range from the arguments.
   if (request.arguments) {
     from_index = request.arguments.fromFrame;
     if (from_index < 0) {
       return response.failed('Invalid frame number');
     }
@@ skipping 305 matching lines @@
       json += NumberToJSON_(elem);
     } else if (IS_STRING(elem)) {
       json += StringToJSON_(elem);
     } else {
       json += elem;
     }
   }
   json += ']';
   return json;
 }