Auto merge of #120586 - ShE3py:exprkind-err, r=fmease

Add `ErrorGuaranteed` to `ast::ExprKind::Err`

See #119967 for context
```
      \
       \
          _~^~^~_
      \) /  o o  \ (/
        '_   -   _'
        / '-----' \
```

r? fmease

compiler/rustc_lint/src/unused.rs

@@ -758,7 +758,7 @@ trait UnusedDelimLint {
         }
         impl<'ast> Visitor<'ast> for ErrExprVisitor {
             fn visit_expr(&mut self, expr: &'ast ast::Expr) {
-                if let ExprKind::Err = expr.kind {
+                if let ExprKind::Err(_) = expr.kind {
                     self.has_error = true;
                     return;
                 }