Reaching a stable list formatting requires formatting twice

### Description

Just a small thing I noticed while packaging stuff for Nixpkgs.

### Small example input

```
[ "hello"

]
```

### Expected output

```
[ "hello" ]
```

### Actual output
after first formatting
```
[
  "hello"
]
```
then after formatting again, it gives the correct
```
[ "hello" ]
```