Remove unused hole AST node variable

crates/frontend/src/ast.rs

@@ -234,7 +234,7 @@ pub fn expr(db: &dyn Database, ast: AstNode) -> Expr {
     use ir::{ExprKind::*, Value::*};
 
     // parse the kind depending on which field is selected
-    let kind = if let Some(val) = ast.get_field(db, "hole") {
+    let kind = if ast.get_field(db, "hole").is_some() {
         Extra(Arc::new(ExprExtra::Hole))
     } else if let Some(var) = ast.get_field(db, "variable") {
         let name = var.contents(db).to_string();