Bug 1469384 - Allow no-useless-removeEventListener to not throw if only one argument is given to an addEventListener call. r=florian

Differential Revision: https://phabricator.services.mozilla.com/D5882

--HG--
extra : moz-landing-system : lando

tools/lint/eslint/eslint-plugin-mozilla/lib/rules/no-useless-removeEventListener.js

@@ -30,7 +30,9 @@ module.exports = function(context) {
       }
 
       let listener = node.arguments[1];
-      if (listener.type != "FunctionExpression" || !listener.body ||
+      if (!listener ||
+          listener.type != "FunctionExpression" ||
+          !listener.body ||
           listener.body.type != "BlockStatement" ||
           !listener.body.body.length ||
           listener.body.body[0].type != "ExpressionStatement" ||

tools/lint/eslint/eslint-plugin-mozilla/package-lock.json

@@ -1,6 +1,6 @@
 {
   "name": "eslint-plugin-mozilla",
-  "version": "0.16.0",
+  "version": "0.16.1",
   "lockfileVersion": 1,
   "requires": true,
   "dependencies": {

tools/lint/eslint/eslint-plugin-mozilla/package.json

@@ -1,6 +1,6 @@
 {
   "name": "eslint-plugin-mozilla",
-  "version": "0.16.0",
+  "version": "0.16.1",
   "description": "A collection of rules that help enforce JavaScript coding standard in the Mozilla project.",
   "keywords": [
     "eslint",

tools/lint/eslint/eslint-plugin-mozilla/tests/no-useless-removeEventListener.js

@@ -57,7 +57,10 @@ ruleTester.run("no-useless-removeEventListener", rule, {
     // Should not reject when there's 2 different variables
     "elt.addEventListener(event1, function listener() {" +
     "  elt.removeEventListener(event2, listener);" +
-    "});"
+    "});",
+
+    // Should not fail if this is a different type of event listener function.
+    "myfunc.addEventListener(listener);",
   ],
   invalid: [
     invalidCode("elt.addEventListener('click', function listener() {" +