Use `file.fail` instead of throwing an error

[wooorm]

Initial checklist

• [X] I read the support docs
• [X] I read the contributing guide
• [X] I agree to follow the code of conduct
• [X] I searched issues and couldn’t find anything (or linked relevant results below)

Problem

https://github.com/rehypejs/rehype-highlight/blob/dd58e3935eef931e02080443883ad0832ed6c7fa/lib/index.js#L111

Solution

This error relates to a node, at a certain place. It should be thrown on the vfile.

Alternatives

n/a