fix: handle cases where the arrow function is an object (#239)

Author: morgante

.grit/patterns/js/es6_arrow_functions.md

@@ -3,8 +3,7 @@ title: Function expressions to arrow functions
 tags: [js, es6, migration]
 ---
 
-Converts function expressions to ES6 arrow functions
-
+Converts function expressions to ES6 arrow functions, including eliminating the `return` statement where possible.
 
 ```grit
 engine marzano(0.1)
@@ -23,7 +22,13 @@ or {
       or { `this`, `arguments` }
     } until `function $_($_) { $_ }`
   },
-  `($args) => { return $value }` => `($args) => $value`
+  `($args) => { return $value }` where {
+    if ($value <: object()) {
+      $result = `($value)`
+    } else {
+      $result = $value
+    }
+  } => `($args) => $result`
 }
 ```
 
@@ -68,3 +73,25 @@ var sumToValue = (x, y) => {
 
 var times = (x, y) => x * y;
 ```
+
+## Wraps objects correctly
+
+An arrow function can return an object directly, but it must be wrapped in parentheses.
+
+```js
+const dummyAnswer = (type) => {
+  return {
+    dataset: function (name, query) {
+      return 1;
+    },
+  };
+};
+```
+
+```js
+const dummyAnswer = (type) => ({
+  dataset: (name, query) => {
+    return 1;
+  },
+});
+```