Description

this PR

• refactors ErrorMake::run to avoid duplicate branches depending on the value of --unspanned
• completes the examples
  1. show a really simple error make call, without any command definition
  2. show a complete error format with all possible fields
  3. the command definition but with indentation and slightly better description
• adds results to the first two examples
• gives meaningful error messages for all known "bad" error formats, using the span of the error format or the span of $format.label to better explain why the format is bad

User-Facing Changes

users have now the following help

Examples:
  Create a simple custom error
  > error make {msg: "my custom error message"}

  Create a more complex custom error
  > error make {
        msg: "my custom error message"
        label: {
            text: "my custom label text"  # not mandatory unless $.label exists
            start: 123  # not mandatory unless $.label.end is set
            end: 456  # not mandatory unless $.label.start is set
        }
    }

  Create a custom error for a custom command that shows the span of the argument
  > def foo [x] {
        let span = (metadata $x).span;
        error make {
            msg: "this is fishy"
            label: {
                text: "fish right here"
                start: $span.start
                end: $span.end
            }
        }
    }

and the following error messages when the error format is bad https://asciinema.org/a/568107 🥳

Tests + Formatting

• 🟢 cargo fmt --all
• 🟢 cargo clippy --workspace -- -D warnings -D clippy::unwrap_used -A clippy::needless_collect
• 🔴 cargo test --workspace
  => the tests do not pass but they do not pass on latest main either => i should cargo clean, but that's an expensive operation on my machine...

After Submitting

the documentation would have to be regenerated over on the website