Add extra test case for async arrow expressions in ternary true branches

Author: Maxim

tests/parsing/grammar/expressions/async.res

@@ -24,4 +24,6 @@ let async = {
     {async: async[async]}
 
     result->async->mapAsync(a => doStuff(a))
-}
+}
+
+let f = isPositive ? (async (a, b) : int => a + b) : async (c, d) : int => c - d

tests/parsing/grammar/expressions/expected/async.res.txt

@@ -20,4 +20,9 @@ let async =
     async.async;
     { async = (async.(async)) };
     (result |. async) |. (mapAsync (fun a -> doStuff a)))
-  [@ns.braces ])
+  [@ns.braces ])
+let f =
+  ((if isPositive
+    then ((fun a -> fun b -> (a + b : int))[@res.async ])
+    else (((fun c -> fun d -> (c - d : int)))[@res.async ]))
+  [@ns.ternary ])