Add linting and formatting

libraries/o-error/.circleci/config.yml

@@ -10,8 +10,9 @@ jobs:
       - node/with-cache:
           steps:
             - run: npm install
+            - run: npm run lint
             - run: npm test
 workflows:
-    build-and-test:
-      jobs:
-        - build-and-test
+  build-and-test:
+    jobs:
+      - build-and-test

libraries/o-error/.editorconfig

@@ -0,0 +1,9 @@
+root = true
+
+[*]
+charset = utf-8
+indent_style = space
+indent_size = 2
+end_of_line = lf
+insert_final_newline = true
+trim_trailing_whitespace = true

libraries/o-error/.eslintrc.json

@@ -0,0 +1,14 @@
+{
+  "extends": [
+    "plugin:prettier/recommended",
+    "plugin:mocha/recommended",
+    "plugin:chai-expect/recommended",
+    "plugin:chai-friendly/recommended"
+  ],
+  "env": {
+    "node": true
+  },
+  "parserOptions": {
+    "ecmaVersion": 2018
+  }
+}

libraries/o-error/.prettierrc.json

@@ -0,0 +1,4 @@
+{
+  "semi": false,
+  "singleQuote": true
+}

libraries/o-error/package.json

@@ -4,6 +4,7 @@
   "description": "Make custom error types that pass `instanceof` checks, have stack traces, support custom messages and properties, and can wrap causes (like VError).",
   "main": "index.js",
   "scripts": {
+    "lint": "eslint .",
     "test": "mocha --require test/support"
   },
   "author": "Overleaf (https://www.overleaf.com)",
@@ -11,6 +12,13 @@
   "repository": "github:overleaf/o-error",
   "devDependencies": {
     "chai": "^3.3.0",
-    "mocha": "^6.1.4"
+    "eslint": "^6.8.0",
+    "eslint-config-prettier": "^6.10.1",
+    "eslint-plugin-chai-expect": "^2.1.0",
+    "eslint-plugin-chai-friendly": "^0.5.0",
+    "eslint-plugin-mocha": "^6.3.0",
+    "eslint-plugin-prettier": "^3.1.3",
+    "mocha": "^7.1.1",
+    "prettier": "^2.0.2"
   }
 }