do not eat nested exprs result in format args visitor

compiler/rustc_ast_lowering/src/format.rs

@@ -604,8 +604,7 @@ fn visit_expr(&mut self, e: &ast::Expr) -> ControlFlow<()> {
             if let ast::ExprKind::Await(_, _) | ast::ExprKind::Yield(_) = e.kind {
                 ControlFlow::Break(())
             } else {
-                visit::walk_expr(self, e);
-                ControlFlow::Continue(())
+                visit::walk_expr(self, e)
             }
         }