* 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
This commit adds the fast and CommonMark compliant Goldmark as the new default markdown handler in Hugo.
If you want to continue using BlackFriday as the default for md/markdown extensions, you can use this configuration:
```toml
[markup]
defaultMarkdownHandler="blackfriday"
```
Fixes#5963Fixes#1778Fixes#6355
