debugger: Don't crash when evaling buffer

lib/_debugger.js

@@ -141,7 +141,7 @@ exports.Client = Client;
 
 Client.prototype._addHandle = function(desc) {
   if (typeof desc != 'object' || typeof desc.handle != 'number') {
-    throw new Error('bad type');
+    return;
   }
 
   this.handles[desc.handle] = desc;
@@ -428,7 +428,13 @@ Client.prototype.mirrorObject = function(handle, cb) {
 
       for (var i = 0; i < handle.properties.length; i++) {
         var value = res.body[handle.properties[i].ref];
-        var mirrorValue = value.value ? value.value : value.text;
+        var mirrorValue;
+        if (value) {
+          mirrorValue = value.value ? value.value : value.text;
+        } else {
+          mirrorValue = '[?]';
+        }
+
 
         if (Array.isArray(mirror) &&
             typeof handle.properties[i].name != 'number') {