feat(Error): adding error metadata field

index.js

@@ -16,6 +16,7 @@ try {
 module.exports = {
   MongoError: require('./lib/error').MongoError,
   MongoNetworkError: require('./lib/error').MongoNetworkError,
+  mongoErrorContextSymbol: require('./lib/error').mongoErrorContextSymbol,
   Connection: require('./lib/connection/connection'),
   Server: require('./lib/topologies/server'),
   ReplSet: require('./lib/topologies/replset'),

lib/cursor.js

@@ -1,10 +1,11 @@
 'use strict';
 
-var Logger = require('./connection/logger'),
-  retrieveBSON = require('./connection/utils').retrieveBSON,
-  MongoError = require('./error').MongoError,
-  MongoNetworkError = require('./error').MongoNetworkError,
-  f = require('util').format;
+const Logger = require('./connection/logger');
+const retrieveBSON = require('./connection/utils').retrieveBSON;
+const MongoError = require('./error').MongoError;
+const MongoNetworkError = require('./error').MongoNetworkError;
+const mongoErrorContextSymbol = require('./error').mongoErrorContextSymbol;
+const f = require('util').format;
 
 var BSON = retrieveBSON(),
   Long = BSON.Long;
@@ -709,7 +710,13 @@ var nextFunction = function(self, callback) {
 
     // Execute the next get more
     self._getmore(function(err, doc, connection) {
-      if (err) return handleCallback(callback, err);
+      if (err) {
+        if (err instanceof MongoError) {
+          err[mongoErrorContextSymbol].isGetMore = true;
+        }
+
+        return handleCallback(callback, err);
+      }
 
       if (self.cursorState.cursorId && self.cursorState.cursorId.isZero() && self._endSession) {
         self._endSession();

lib/error.js

@@ -2,6 +2,8 @@
 
 var util = require('util');
 
+const mongoErrorContextSymbol = Symbol('mongoErrorContextSymbol');
+
 /**
  * Creates a new MongoError
  * @class
@@ -31,6 +33,8 @@ function MongoError(message) {
       Error.captureStackTrace(this, this.constructor);
     }
   }
+
+  this[mongoErrorContextSymbol] = this[mongoErrorContextSymbol] || {};
 }
 util.inherits(MongoError, Error);
 
@@ -94,5 +98,6 @@ module.exports = {
   MongoError,
   MongoNetworkError,
   MongoParseError,
-  MongoTimeoutError
+  MongoTimeoutError,
+  mongoErrorContextSymbol
 };