Better generic errors for plugins (and perhaps scripts) (#12236)

# Description
This makes `LabeledError` much more capable of representing close to
everything a `miette::Diagnostic` can, including `ShellError`, and
allows plugins to generate multiple error spans, codes, help, etc.

`LabeledError` is now embeddable within `ShellError` as a transparent
variant.

This could also be used to improve `error make` and `try/catch` to
reflect `LabeledError` exactly in the future.

Also cleaned up some errors in existing plugins.

# User-Facing Changes
Breaking change for plugins. Nicer errors for users.

crates/nu_plugin_inc/src/inc.rs

@@ -1,5 +1,4 @@
-use nu_plugin::LabeledError;
-use nu_protocol::{ast::CellPath, Span, Value};
+use nu_protocol::{ast::CellPath, LabeledError, Span, Value};
 use semver::{BuildMetadata, Prerelease, Version};
 
 #[derive(Debug, Eq, PartialEq, Clone, Copy)]
@@ -102,12 +101,7 @@ impl Inc {
             let cell_value = self.inc_value(head, &cell_value)?;
 
             let mut value = value.clone();
-            value
-                .update_data_at_cell_path(&cell_path.members, cell_value)
-                .map_err(|x| {
-                    let error: LabeledError = x.into();
-                    error
-                })?;
+            value.update_data_at_cell_path(&cell_path.members, cell_value)?;
             Ok(value)
         } else {
             self.inc_value(head, value)
@@ -119,17 +113,14 @@ impl Inc {
             Value::Int { val, .. } => Ok(Value::int(val + 1, head)),
             Value::String { val, .. } => Ok(self.apply(val, head)),
             x => {
-                let msg = x.coerce_string().map_err(|e| LabeledError {
-                    label: "Unable to extract string".into(),
-                    msg: format!("value cannot be converted to string {x:?} - {e}"),
-                    span: Some(head),
+                let msg = x.coerce_string().map_err(|e| {
+                    LabeledError::new("Unable to extract string").with_label(
+                        format!("value cannot be converted to string {x:?} - {e}"),
+                        head,
+                    )
                 })?;
 
-                Err(LabeledError {
-                    label: "Incorrect value".into(),
-                    msg,
-                    span: Some(head),
-                })
+                Err(LabeledError::new("Incorrect value").with_label(msg, head))
             }
         }
     }

crates/nu_plugin_inc/src/nu/mod.rs

@@ -1,9 +1,7 @@
 use crate::inc::SemVerAction;
 use crate::Inc;
-use nu_plugin::{
-    EngineInterface, EvaluatedCall, LabeledError, Plugin, PluginCommand, SimplePluginCommand,
-};
-use nu_protocol::{ast::CellPath, PluginSignature, SyntaxShape, Value};
+use nu_plugin::{EngineInterface, EvaluatedCall, Plugin, PluginCommand, SimplePluginCommand};
+use nu_protocol::{ast::CellPath, LabeledError, PluginSignature, SyntaxShape, Value};
 
 pub struct IncPlugin;