"No else after return" is a common rule.  It means that if you return something in an if, you don't need an else after it:

```javascript
if (condition1) {
  return value1;
}
// condition2 is implied here
return value2

A better way to write this is to do:

```javascript
return langmap[locale] || "Unknown";
```
Also, `langmap` should probably be `langMap`.