diff --git a/lib/Compilation.ts b/lib/Compilation.ts
index 5469d47d8a6..4324acbeea1 100644
--- a/lib/Compilation.ts
+++ b/lib/Compilation.ts
@@ -1037,11 +1037,12 @@ class Compilation extends Tapable {
         for (let i = 0; i < this.modules.length; i++) {
             const module = this.modules[i];
             if (module.assets) {
-                Object.keys(module.assets).forEach(function (name) {
-                    const file = this.getPath(name);
-                    this.assets[file] = module.assets[name];
-                    this.applyPlugins('module-asset', module, file);
-                }, this);
+                Object.keys(module.assets)
+                    .forEach(name => {
+                        const file = this.getPath(name);
+                        this.assets[file] = module.assets[name];
+                        this.applyPlugins('module-asset', module, file);
+                    });
             }
         }
     }
diff --git a/lib/Parser.ts b/lib/Parser.ts
index 28643448770..a5e8bae2934 100644
--- a/lib/Parser.ts
+++ b/lib/Parser.ts
@@ -20,12 +20,12 @@ const POSSIBLE_AST_OPTIONS = [
     {
         ranges: true,
         locations: true,
-        ecmaVersion: 6,
+        ecmaVersion: 2017,
         sourceType: 'module'
     }, {
         ranges: true,
         locations: true,
-        ecmaVersion: 6,
+        ecmaVersion: 2017,
         sourceType: 'script'
     }
 ] as ASTOPTION[];
@@ -829,6 +829,13 @@ class Parser extends Tapable {
         }
     }
 
+    walkAwaitExpression(expression) {
+        const argument = expression.argument
+        if (this["walk" + argument.type]) {
+            return this["walk" + argument.type](argument);
+        }
+    }
+
     walkSpreadElement(expression) {
         if (expression.argument) {
             this.walkExpression(expression.argument);
@@ -1105,7 +1112,7 @@ class Parser extends Tapable {
     }
 
     enterPattern(pattern, onIdent) {
-        if (this[`enter${pattern.type}`]) {
+        if (pattern != null && this[`enter${pattern.type}`]) {
             return this[`enter${pattern.type}`](pattern, onIdent);
         }
     }
@@ -1251,7 +1258,7 @@ class Parser extends Tapable {
             ast = acorn.parse(source, {
                 ranges: true,
                 locations: true,
-                ecmaVersion: 6,
+                ecmaVersion: 2017,
                 sourceType: 'module',
                 onComment: comments
             });
@@ -1279,7 +1286,7 @@ class Parser extends Tapable {
         const ast = acorn.parse(`(${source})`, {
             ranges: true,
             locations: true,
-            ecmaVersion: 6,
+            ecmaVersion: 2017,
             sourceType: 'module'
         });
         if (!ast || typeof ast !== 'object' || ast.type !== 'Program') {
diff --git a/lib/RuleSet.ts b/lib/RuleSet.ts
index cb1bea9a788..a0fa88d0860 100644
--- a/lib/RuleSet.ts
+++ b/lib/RuleSet.ts
@@ -51,7 +51,7 @@
  <condition>: { and: [<condition>] }
  <condition>: { or: [<condition>] }
  <condition>: { not: [<condition>] }
- <condition>: { test: <condition>, include: <condition>, exclude: <codition> }
+ <condition>: { test: <condition>, include: <condition>, exclude: <condition> }
 
 
  normalized:
@@ -163,20 +163,33 @@ class RuleSet {
 
         if (rule.test || rule.include || rule.exclude) {
             checkResourceSource('test + include + exclude');
-            newRule.resource = RuleSet.normalizeCondition({
+            let condition = {
                 test: rule.test,
                 include: rule.include,
                 exclude: rule.exclude
-            });
+            };
+            try {
+                newRule.resource = RuleSet.normalizeCondition(condition);
+            } catch(error) {
+                throw new Error(RuleSet.buildErrorMessage(condition, error));
+            }
         }
 
         if (rule.resource) {
             checkResourceSource('resource');
-            newRule.resource = RuleSet.normalizeCondition(rule.resource);
+            try {
+                newRule.resource = RuleSet.normalizeCondition(rule.resource);
+            } catch(error) {
+                throw new Error(RuleSet.buildErrorMessage(rule.resource, error));
+            }
         }
 
         if (rule.issuer) {
-            newRule.issuer = RuleSet.normalizeCondition(rule.issuer);
+            try {
+                newRule.issuer = RuleSet.normalizeCondition(rule.issuer);
+            } catch(error) {
+                throw new Error(RuleSet.buildErrorMessage(rule.issuer, error));
+            }
         }
 
         if (rule.loader && rule.loaders) {
@@ -350,6 +363,15 @@ class RuleSet {
         return andMatcher(matchers);
     }
 
+    static buildErrorMessage(condition, error) {
+        const conditionAsText = JSON.stringify(
+            condition,
+            (key, value) => value === undefined ? "undefined" : value,
+            2
+        )
+        return error.message + " in " + conditionAsText;
+    }
+
     exec(data) {
         const result = [];
         this._run(data, {
diff --git a/lib/UmdMainTemplatePlugin.ts b/lib/UmdMainTemplatePlugin.ts
index 5041f37a88e..64669bcc803 100644
--- a/lib/UmdMainTemplatePlugin.ts
+++ b/lib/UmdMainTemplatePlugin.ts
@@ -153,7 +153,7 @@ ${(externals.length > 0
                     +
                     `})(this, function(${externalsArguments(externals)}) {\nreturn `, 'webpack/universalModuleDefinition'),
                 source,
-                '\n});\n'
+                ';\n})'
             );
         });
         mainTemplate.plugin('global-hash-paths', paths => {
diff --git a/lib/WebpackOptionsDefaulter.ts b/lib/WebpackOptionsDefaulter.ts
index 5eccab07692..c15e64c7121 100644
--- a/lib/WebpackOptionsDefaulter.ts
+++ b/lib/WebpackOptionsDefaulter.ts
@@ -94,7 +94,6 @@ class WebpackOptionsDefaulter extends OptionsDefaulter {
         this.set('resolveLoader.unsafeCache', true);
         this.set('resolveLoader.mainFields', ['loader', 'main']);
         this.set('resolveLoader.extensions', ['.js', '.json']);
-        this.set('resolveLoader.moduleExtensions', ['-loader']);
     }
 }
 
diff --git a/lib/WebpackOptionsValidationError.ts b/lib/WebpackOptionsValidationError.ts
index 7c7b84d9613..1a45b3cf5be 100644
--- a/lib/WebpackOptionsValidationError.ts
+++ b/lib/WebpackOptionsValidationError.ts
@@ -65,6 +65,8 @@ For loader options: webpack 2 no longer allows custom properties in configuratio
                         return `${dataPath} should be a number.`;
                 }
                 return `${dataPath} should be ${err.params.type}:\n${getSchemaPartText(err.parentSchema)}`;
+            case "instanceof":
+                return `${dataPath} should be an instance of ${getSchemaPartText(err.parentSchema)}.`;
             case 'required':
                 const missingProperty = err.params.missingProperty.replace(/^\./, '');
                 return `${dataPath} misses the property '${missingProperty}'.\n${getSchemaPartText(err.parentSchema, [
diff --git a/lib/validateWebpackOptions.ts b/lib/validateSchema.ts
similarity index 71%
rename from lib/validateWebpackOptions.ts
rename to lib/validateSchema.ts
index ada97ef69f8..2efbc96da11 100644
--- a/lib/validateWebpackOptions.ts
+++ b/lib/validateSchema.ts
@@ -1,9 +1,9 @@
 /*
- MIT License http://www.opensource.org/licenses/mit-license.php
- Author Gajus Kuizinas @gajus
- */
+	MIT License http://www.opensource.org/licenses/mit-license.php
+	Author Gajus Kuizinas @gajus
+*/
 import Ajv = require('ajv');
-const webpackOptionsSchema = require('../schemas/webpackOptionsSchema.json');
+import defineKeywords = require('ajv-keywords')
 
 const ajv = new Ajv({
     errorDataPath: 'configuration',
@@ -11,14 +11,16 @@ const ajv = new Ajv({
     verbose: true
 });
 
-const validate = ajv.compile(webpackOptionsSchema);
+defineKeywords(ajv);
 
-function validateWebpackOptions(options) {
+function validateSchema(schema, options) {
+    const validate = ajv.compile(schema);
     if (Array.isArray(options)) {
         const errors = options.map(validateObject);
-        errors.forEach((list, idx) => {
+
+        errors.forEach(function (list, idx) {
             list.forEach(function applyPrefix(err) {
-                err.dataPath = `[${idx}]${err.dataPath}`;
+                err.dataPath = "[" + idx + "]" + err.dataPath;
                 if (err.children) {
                     err.children.forEach(applyPrefix);
                 }
@@ -29,11 +31,11 @@ function validateWebpackOptions(options) {
     else {
         return validateObject(options);
     }
-}
 
-function validateObject(options) {
-    const valid = validate(options);
-    return valid ? [] : filterErrors(validate.errors);
+    function validateObject(options) {
+        const valid = validate(options);
+        return valid ? [] : filterErrors(validate.errors);
+    }
 }
 
 function filterErrors(errors) {
@@ -62,4 +64,4 @@ function filterErrors(errors) {
     return newErrors;
 }
 
-export = validateWebpackOptions;
+export = validateSchema;
diff --git a/lib/webpack.ts b/lib/webpack.ts
index a8371a9aded..6d64286f7a8 100644
--- a/lib/webpack.ts
+++ b/lib/webpack.ts
@@ -7,14 +7,16 @@ import MultiCompiler = require('./MultiCompiler');
 import NodeEnvironmentPlugin = require('./node/NodeEnvironmentPlugin');
 import WebpackOptionsApply = require('./WebpackOptionsApply');
 import WebpackOptionsDefaulter = require('./WebpackOptionsDefaulter');
-import validateWebpackOptions = require('./validateWebpackOptions');
+import validateSchema = require("./validateSchema");
 import WebpackOptionsValidationError = require('./WebpackOptionsValidationError');
 
+const webpackOptionsSchema = require("../schemas/webpackOptionsSchema.json");
+
 function webpack(options, callback): Watching
 function webpack(options): MultiCompiler | Compiler
 
 function webpack(options, callback?) {
-    const webpackOptionsValidationErrors = validateWebpackOptions(options);
+    const webpackOptionsValidationErrors = validateSchema(webpackOptionsSchema, options);
     if (webpackOptionsValidationErrors.length) {
         throw new WebpackOptionsValidationError(webpackOptionsValidationErrors);
     }
@@ -57,7 +59,9 @@ webpack.WebpackOptionsApply = WebpackOptionsApply;
 webpack.Compiler = Compiler;
 webpack.MultiCompiler = MultiCompiler;
 webpack.NodeEnvironmentPlugin = NodeEnvironmentPlugin;
-webpack.validate = validateWebpackOptions;
+webpack.validate = validateSchema.bind(this, webpackOptionsSchema);
+webpack.validateSchema = validateSchema;
+webpack.WebpackOptionsValidationError = WebpackOptionsValidationError;
 
 function exportPlugins(exports, path, plugins) {
     plugins.forEach(name => {