Screen reader-friendly errors (#10122)

- Hopefully closes #10120  

# Description

This PR adds a new config item, `error_style`. It will render errors in
a screen reader friendly mode when set to `"simple"`. This is done using
`miette`'s own `NarratableReportHandler`, which seamlessly replaces the
default one when needed.

Before:
```
Error: nu::shell::external_command

  × External command failed
   ╭─[entry #2:1:1]
 1 │ doesnt exist
   · ───┬──
   ·    ╰── executable was not found
   ╰────
  help: No such file or directory (os error 2)
```

After:
```
Error: External command failed
    Diagnostic severity: error
Begin snippet for entry #4 starting at line 1, column 1

snippet line 1: doesnt exist
    label at line 1, columns 1 to 6: executable was not found
diagnostic help: No such file or directory (os error 2)
diagnostic code: nu::shell::external_command

```

## Things to be determined

- ~Review naming. `errors.style` is not _that_ consistent with the rest
of the code. Menus use a `style` record, but table rendering mode is set
via `mode`.~ As it's a single config, we're using `error_style` for now.
- Should this kind of setting be toggable with one single parameter?
`accessibility.no_decorations` or similar, which would adjust the style
of both errors and tables accordingly.

# User-Facing Changes

No changes by default, errors will be rendered differently if
`error_style` is set to `simple`.

# Tests + Formatting
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# After Submitting

There's a PR updating the docs over here
nushell/nushell.github.io#1026

crates/nu-protocol/src/cli_error.rs

@@ -1,5 +1,8 @@
 use crate::engine::{EngineState, StateWorkingSet};
-use miette::{LabeledSpan, MietteHandlerOpts, ReportHandler, RgbColors, Severity, SourceCode};
+use miette::{
+ LabeledSpan, MietteHandlerOpts, NarratableReportHandler, ReportHandler, RgbColors, Severity,
+ SourceCode,
+};
 use thiserror::Error;
 
 /// This error exists so that we can defer SourceCode handling. It simply
@@ -41,16 +44,27 @@ pub fn report_error_new(
 
 impl std::fmt::Debug for CliError<'_> {
  fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
- let ansi_support = self.1.get_config().use_ansi_coloring;
-
- let miette_handler = MietteHandlerOpts::new()
- // For better support of terminal themes use the ANSI coloring
- .rgb_colors(RgbColors::Never)
- // If ansi support is disabled in the config disable the eye-candy
- .color(ansi_support)
- .unicode(ansi_support)
- .terminal_links(ansi_support)
- .build();
+ let config = self.1.get_config();
+
+ let ansi_support = &config.use_ansi_coloring;
+ let ansi_support = *ansi_support;
+
+ let error_style = &config.error_style.as_str();
+ let errors_style = *error_style;
+
+ let miette_handler: Box<dyn ReportHandler> = match errors_style {
+ "plain" => Box::new(NarratableReportHandler::new()),
+ _ => Box::new(
+ MietteHandlerOpts::new()
+ // For better support of terminal themes use the ANSI coloring
+ .rgb_colors(RgbColors::Never)
+ // If ansi support is disabled in the config disable the eye-candy
+ .color(ansi_support)
+ .unicode(ansi_support)
+ .terminal_links(ansi_support)
+ .build(),
+ ),
+ };
 
  // Ignore error to prevent format! panics. This can happen if span points at some
  // inaccessible location, for example by calling `report_error()` with wrong working set.

crates/nu-protocol/src/config.rs

@@ -26,7 +26,7 @@ pub struct ParsedMenu {
  pub source: Value,
 }
 
-/// Definition of a parsed menu from the config object
+/// Definition of a parsed hook from the config object
 #[derive(Serialize, Deserialize, Clone, Debug)]
 pub struct Hooks {
  pub pre_prompt: Option<Value>,
@@ -113,6 +113,7 @@ pub struct Config {
  pub cursor_shape_emacs: NuCursorShape,
  pub datetime_normal_format: Option<String>,
  pub datetime_table_format: Option<String>,
+ pub error_style: String,
 }
 
 impl Default for Config {
@@ -175,6 +176,8 @@ impl Default for Config {
  menus: Vec::new(),
 
  keybindings: Vec::new(),
+
+ error_style: "fancy".into(),
  }
  }
 }
@@ -1322,6 +1325,14 @@ impl Value {
  );
  }
  }
+ "error_style" => {
+ if let Ok(style) = value.as_string() {
+ config.error_style = style;
+ } else {
+ invalid!(Some(span), "should be a string");
+ vals[index] = Value::string(config.error_style.clone(), span);
+ }
+ }
  // Catch all
  x => {
  invalid_key!(

crates/nu-protocol/tests/test_config.rs

@@ -49,3 +49,58 @@ fn filesize_format_auto_metric_false() {
  let actual = nu!(nu_repl_code(code));
  assert_eq!(actual.out, r#"["1.9 MiB", "1.9 GiB", "1.8 TiB"]"#);
 }
+
+#[test]
+fn fancy_default_errors() {
+ let actual = nu!(nu_repl_code(&[
+ r#"def force_error [x] {
+ let span = (metadata $x).span;
+ error make {
+ msg: "oh no!"
+ label: {
+ text: "here's the error"
+ start: $span.start
+ end: $span.end
+ }
+ }
+ }"#,
+ r#"force_error "My error""#
+ ]));
+
+ assert_eq!(
+ actual.err,
+ "Error: \u{1b}[31m×\u{1b}[0m oh no!\n ╭─[\u{1b}[36;1;4mline1\u{1b}[0m:1:1]\n \u{1b}[2m1\u{1b}[0m │ force_error \"My error\"\n · \u{1b}[35;1m ─────┬────\u{1b}[0m\n · \u{1b}[35;1m╰── \u{1b}[35;1mhere's the error\u{1b}[0m\u{1b}[0m\n ╰────\n\n\n"
+ );
+}
+
+#[test]
+fn narratable_errors() {
+ let actual = nu!(nu_repl_code(&[
+ r#"$env.config = { error_style: "plain" }"#,
+ r#"def force_error [x] {
+ let span = (metadata $x).span;
+ error make {
+ msg: "oh no!"
+ label: {
+ text: "here's the error"
+ start: $span.start
+ end: $span.end
+ }
+ }
+ }"#,
+ r#"force_error "my error""#,
+ ]));
+
+ assert_eq!(
+ actual.err,
+ r#"Error: oh no!
+ Diagnostic severity: error
+Begin snippet for line2 starting at line 1, column 1
+
+snippet line 1: force_error "my error"
+ label at line 1, columns 13 to 22: here's the error
+
+
+"#,
+ );
+}

crates/nu-utils/src/sample_config/default_config.nu

@@ -167,6 +167,8 @@ $env.config = {
  header_on_separator: false # show header text on separator/border line
  }
 
+ error_style: "fancy" # "fancy" or "plain" for screen reader-friendly error messages
+
  # datetime_format determines what a datetime rendered in the shell would look like.
  # Behavior without this configuration point will be to "humanize" the datetime display,
  # showing something like "a day ago."