Undefined when converting array with strings

Here is the code 

```
var remapped = require('remapped');
var source = {
  arr: ["0", "1", "2"],
};
var mapping = {
  myarr: 'arr',
};
remapped(source, mapping);
```

The result is 
```
Object
myarr: Array[3]
0: undefined
1: undefined
2: undefined
```
It work is array consists of integers