validateQuoteMarks: do not throw on es7 decorators

Fixes #2141

Author: markelog

lib/rules/validate-quote-marks.js

@@ -113,11 +113,14 @@ module.exports.prototype = {
             '\'': '"'
         };
         file.iterateTokensByType('String', function(token) {
-            if (
-                ignoreJSX &&
-                file.getNodeByRange(token.range[0]).parentNode.type === 'JSXAttribute'
-            ) {
-                return;
+            var node;
+
+            if (ignoreJSX) {
+                node = file.getNodeByRange(token.range[0]).parentNode;
+
+                if (node && node.type === 'JSXAttribute') {
+                    return;
+                }
             }
 
             var str = token.value;

test/specs/rules/validate-quote-marks.js

@@ -44,6 +44,15 @@ describe('rules/validate-quote-marks', function() {
             var str = '<div className="flex-card__header">{this.props.children}</div>;';
             expect(checker.checkString(str)).to.have.errors.from('validateQuoteMarks');
         });
+
+        it('should not throw for es7 decorators', function() {
+            checker.configure({
+                validateQuoteMarks: { mark: '"', ignoreJSX: true, escape: true },
+                esnext: true
+            });
+            var str = '@foo (s => "1") export default class Bar {}';
+            expect(checker.checkString(str)).to.have.no.errors();
+        });
     });
 
     describe('option value \' ', function() {