diff --git a/lib/js-yaml/loader.js b/lib/js-yaml/loader.js
index da757ee7..2a244aaf 100644
--- a/lib/js-yaml/loader.js
+++ b/lib/js-yaml/loader.js
@@ -1,6 +1,6 @@
 'use strict';
 
-/*eslint-disable max-len,no-use-before-define,no-unused-vars*/
+/*eslint-disable max-len,no-use-before-define*/
 
 var common              = require('./common');
 var YAMLException       = require('./exception');
@@ -949,7 +949,7 @@ function readBlockScalar(state, nodeIndent) {
 
 function readBlockSequence(state, nodeIndent) {
   var _line,
-      _pos,
+      //_pos,
       _tag      = state.tag,
       _anchor   = state.anchor,
       _result   = [],
@@ -987,7 +987,7 @@ function readBlockSequence(state, nodeIndent) {
     }
 
     _line = state.line;
-    _pos = state.position;
+    //_pos = state.position;
     composeNode(state, nodeIndent, CONTEXT_BLOCK_IN, false, true);
     //addMetaInformation(state, _result, keyNode, _line, _pos);
     _result.push(state.result);
@@ -1478,8 +1478,6 @@ function readDocument(state) {
   var _position,
       iterator,
       doc,
-      index,
-      length,
       directiveName,
       directiveArgs,
       hasDirectives = false,
@@ -1574,6 +1572,9 @@ function readDocument(state) {
   iterator = state.documentListener;
   var expectAnotherYamlChunk = false;
   if (iterator) {
+    if (typeof iterator !== 'function') {
+      throwError(state, 'document listener (iterator) must be a FUNCTION or NULL, not a ' + typeof iterator);
+    }
     expectAnotherYamlChunk = !!iterator(doc, state.documents.length - 1, state);
     if (expectAnotherYamlChunk) {
       skipSeparationSpace(state, true, -1);
@@ -1581,7 +1582,6 @@ function readDocument(state) {
   }
 
   if (state.position === state.lineStart && testDocumentSeparator(state)) {
-
     if (state.input.charCodeAt(state.position) === 0x2E/* . */) {
       state.position += 3;
       skipSeparationSpace(state, true, -1);
@@ -1651,11 +1651,8 @@ function load(input, options) {
 }
 
 
-function safeLoadAll(input, output, options) {
-  if (typeof output !== 'function') {
-    output = null;
-  }
-  return loadAll(input, output, common.extend({ schema: DEFAULT_SAFE_SCHEMA }, options));
+function safeLoadAll(input, iterator, options) {
+  return loadAll(input, iterator, common.extend({ schema: DEFAULT_SAFE_SCHEMA }, options));
 }