* Add file context to minifier errors when publishing
* Misc fixes (see issues)
* Allow custom server error template in layouts/server/error.html
To get to this, this commit also cleans up and simplifies the code surrounding errors and files. This also removes the usage of `github.com/pkg/errors`, mostly because of https://github.com/pkg/errors/issues/223 -- but also because most of this is now built-in to Go.
Fixes#9852Fixes#9857Fixes#9863
The main use case for this is to use with resources.PostProcess and resources.PostCSS with purgecss.
You would normally set it up to extract keywords from your templates, doing it from the full /public takes forever for bigger sites.
Doing the template thing misses dynamically created class names etc., and it's hard/impossible to set up in when using themes.
You can enable this in your site config:
```toml
[build]
writeStats = true
```
It will then write a `hugo_stats.json` file to the project root as part of the build.
If you're only using this for the production build, you should consider putting it below `config/production`.
You can then set it up with PostCSS like this:
```js
const purgecss = require('@fullhuman/postcss-purgecss')({
content: [ './hugo_stats.json' ],
defaultExtractor: (content) => {
let els = JSON.parse(content).htmlElements;
return els.tags.concat(els.classes, els.ids);
}
});
module.exports = {
plugins: [
require('tailwindcss'),
require('autoprefixer'),
...(process.env.HUGO_ENVIRONMENT === 'production' ? [ purgecss ] : [])
]
};
```
Fixes#6999
