confusing error messages when loading lists with heterogeneous elements

The error messages are printed the other way around. For example:

```
$ echo '[1, {"id":1}]' | bin/comp -t json 'in'
failed to load in.json: expected object, got scalar (map[id:1])
```

instead it should be

```
$ echo '[1, {"id":1}]' | bin/comp -t json 'in'
failed to load in.json: expected scalar, got object (map[id:1])
```
