bat panics on simple Vue file

When calling `bat` on this Vue file
``` vue
<style lang="stylus">
</style>
```
it panics with:
```
thread 'main' panicked at
  'Can only call resolve on linked references:
    ByScope { scope: <source.stylus>, sub_context: None }',
  …/syntect-4.1.0/src/parsing/syntax_definition.rs:188:18
```

found with the Python script in #913.