Set up eslint and fix a small number of issues

.eslintrc.js

@@ -0,0 +1,12 @@
+module.exports = {
+  extends: "eslint:recommended",
+  parserOptions: {
+    ecmaVersion: 2018,
+    sourceType: "module"
+  },
+  env: {
+    mocha: true,
+    node: true,
+    es6: true,
+  }
+};

.travis.yml

@@ -6,7 +6,7 @@ install:
   - npm install
 
 script:
-  - npm test
+  - npm run lint && npm test
 
 # Allow Travis tests to run in containers.
 sudo: false

package.json

@@ -8,7 +8,8 @@
     "test": "tav --ci && mocha test/index.js",
     "prepublish": "babel ./src --ignore test --out-dir ./lib",
     "pretest": "node test/updateSchemaJson.js",
-    "tav": "tav"
+    "tav": "tav",
+    "lint": "eslint src/**/*.js test/**/*.js"
   },
   "homepage": "https://github.com/apollostack/eslint-plugin-graphql",
   "repository": {

src/index.js

@@ -11,7 +11,6 @@ import {
 import {
   flatten,
   keys,
-  last,
   reduce,
   without,
   includes,
@@ -383,7 +382,7 @@ function handleTemplateTag(node, context, schema, env, validators) {
     text = replaceExpressions(node.quasi, context, env);
   } catch (e) {
     if (e.message !== 'Invalid interpolation') {
-      console.log(e);
+      console.log(e); // eslint-disable-line no-console
     }
     return;
   }