unified: Fix fields in await_expression

This required a change in a different place, due to aliasing.

unified/extractor/tree-sitter-swift/grammar.js

@@ -1237,7 +1237,7 @@ module.exports = grammar({
       //
       // To fix that, we simply undo the special casing by defining our own `await_expression`.
       choice($.expression, alias($.for_statement_await, $.await_expression)),
-    for_statement_await: ($) => seq($._await_operator, $.expression),
+    for_statement_await: ($) => seq($._await_operator, field("expr", $.expression)),
 
     while_statement: ($) =>
       prec(

unified/extractor/tree-sitter-swift/node-types.yml

@@ -144,8 +144,7 @@ named:
   availability_condition:
     $children*: [identifier, integer_literal]
   await_expression:
-    $children?: expression
-    expr?: expression
+    expr: expression
   bang:
   bin_literal:
   bitwise_operation: