avoid panic when using from nuon (nushell#7533)

# Description

Fixes nushell#5996 

Just found a relative easy way to fix the issue

# User-Facing Changes

```
❯ open $nu.plugin-path | from nuon
Error:
  × error when loading nuon text
   ╭─[entry nushell#36:1:1]
 1 │ open $nu.plugin-path | from nuon
   ·                        ────┬────
   ·                            ╰── could not load nuon text
   ╰────

Error:
  × Error when loading


❯ open $nu.config-path | from nuon
Error:
  × error when loading nuon text
   ╭─[entry nushell#37:1:1]
 1 │ open $nu.config-path | from nuon
   ·                        ────┬────
   ·                            ╰── could not load nuon text
   ╰────

Error:
  × error when loading
```

# Tests + Formatting

Don't forget to add tests that cover your changes.

Make sure you've run and fixed any issues with these commands:

- `cargo fmt --all -- --check` to check standard code formatting (`cargo
fmt --all` applies these changes)
- `cargo clippy --workspace -- -D warnings -D clippy::unwrap_used -A
clippy::needless_collect` to check that you're using the standard code
style
- `cargo test --workspace` to check that all tests pass

# After Submitting

If your PR had any user-facing changes, update [the
documentation](https://github.com/nushell/nushell.github.io) after the
PR is merged, if necessary. This will help us keep the docs up to date.

crates/nu-command/src/formats/from/nuon.rs

@@ -56,27 +56,20 @@ impl Command for FromNuon {
 
     fn run(
         &self,
-        _engine_state: &EngineState,
+        engine_state: &EngineState,
         _stack: &mut Stack,
         call: &Call,
         input: PipelineData,
     ) -> Result<nu_protocol::PipelineData, ShellError> {
         let head = call.head;
         let (string_input, metadata) = input.collect_string_strict(head)?;
 
-        let engine_state = EngineState::new();
+        let engine_state = engine_state.clone();
 
         let mut working_set = StateWorkingSet::new(&engine_state);
-
-        let _ = working_set.add_file("nuon file".to_string(), string_input.as_bytes());
-
         let mut error = None;
-
-        // Most of the 'work' in converting from Nuon is simply pushing it through the Nu parser.
-        let (lexed, err) = nu_parser::lex(string_input.as_bytes(), 0, &[b'\n', b'\r'], &[], true);
-        error = error.or(err);
-
-        let (mut block, err) = nu_parser::parse_block(&mut working_set, &lexed, true, &[], false);
+        let (mut block, err) =
+            nu_parser::parse(&mut working_set, None, string_input.as_bytes(), false, &[]);
         error = error.or(err);
 
         if let Some(pipeline) = block.pipelines.get(1) {

crates/nu-command/tests/format_conversions/nuon.rs

@@ -340,6 +340,14 @@ fn quotes_some_strings_necessarily() {
     assert_eq!(actual.out, "list<string>");
 }
 
+#[test]
+fn read_code_should_fail_rather_than_panic() {
+    let actual = nu!(cwd: "tests/fixtures/formats", pipeline(
+        r#"open code.nu | from nuon"#
+    ));
+    assert!(actual.err.contains("error when parsing"))
+}
+
 proptest! {
     #[test]
     fn to_nuon_from_nuon(c: char) {

tests/fixtures/formats/code.nu

@@ -0,0 +1 @@
+register