refactor(BulkOp): remove code that is not used

Author: daprahamian

lib/bulk/common.js

@@ -13,10 +13,7 @@ const executeOperation = require('../utils').executeOperation;
 const isPromiseLike = require('../utils').isPromiseLike;
 
 // Error codes
-const UNKNOWN_ERROR = 8;
-const INVALID_BSON_ERROR = 22;
 const WRITE_CONCERN_ERROR = 64;
-const MULTIPLE_ERROR = 65;
 
 // Insert types
 const INSERT = 1;
@@ -1145,20 +1142,8 @@ Object.defineProperty(BulkOperationBase.prototype, 'length', {
 module.exports = {
  Batch,
  BulkOperationBase,
- BulkWriteError,
- BulkWriteResult,
  bson,
- FindOperators,
- handleMongoWriteConcernError,
- LegacyOp,
- mergeBatchResults,
- INVALID_BSON_ERROR: INVALID_BSON_ERROR,
- MULTIPLE_ERROR: MULTIPLE_ERROR,
- UNKNOWN_ERROR: UNKNOWN_ERROR,
- WRITE_CONCERN_ERROR: WRITE_CONCERN_ERROR,
  INSERT: INSERT,
  UPDATE: UPDATE,
- REMOVE: REMOVE,
- WriteError,
- WriteConcernError
+ REMOVE: REMOVE
 };