ensure error in else is forwarded appropriately (#7411)

# Description

Fixes #7407. 

```
/home/gabriel/CodingProjects/nushell〉if false { 'a' } else { $foo }    12/09/2022 08:14:48 PM
Error: nu::parser::variable_not_found (link)

  × Variable not found.
   ╭─[entry #1:1:1]
 1 │ if false { 'a' } else { $foo }
   ·                         ──┬─
   ·                           ╰── variable not found
   ╰────
```

# User-Facing Changes

_(List of all changes that impact the user experience here. This helps
us keep track of breaking changes.)_

# 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-parser/src/parser.rs

@@ -645,25 +645,33 @@ pub fn parse_multispan_value(
  (arg, error)
  }
  SyntaxShape::OneOf(shapes) => {
+ let mut err = None;
  for shape in shapes.iter() {
- if let (s, None) = parse_multispan_value(
+ let (s, option_err) = parse_multispan_value(
  working_set,
  spans,
  spans_idx,
  shape,
  expand_aliases_denylist,
- ) {
- return (s, None);
+ );
+ match option_err {
+ None => return (s, None),
+ e => err = err.or(e),
  }
  }
  let span = spans[*spans_idx];
- (
- Expression::garbage(span),
- Some(ParseError::Expected(
- format!("one of a list of accepted shapes: {:?}", shapes),
- span,
- )),
- )
+
+ if err.is_some() {
+ (Expression::garbage(span), err)
+ } else {
+ (
+ Expression::garbage(span),
+ Some(ParseError::Expected(
+ format!("one of a list of accepted shapes: {:?}", shapes),
+ span,
+ )),
+ )
+ }
  }
  SyntaxShape::Expression => {
  trace!("parsing: expression");

crates/nu-parser/tests/test_parser.rs

@@ -1402,4 +1402,23 @@ mod input_types {
  assert!(block.len() == 2, "testing: {}", input);
  }
  }
+
+ #[test]
+ fn else_errors_correctly() {
+ let mut engine_state = EngineState::new();
+ add_declations(&mut engine_state);
+
+ let mut working_set = StateWorkingSet::new(&engine_state);
+ let (_, err) = parse(
+ &mut working_set,
+ None,
+ b"if false { 'a' } else { $foo }",
+ true,
+ &[],
+ );
+
+ let err = err.unwrap();
+
+ assert!(matches!(err, ParseError::VariableNotFound(_)));
+ }
 }