Fix async call detection for stdlib context

trans/transpiler/phases/typing/expr.py

@@ -98,7 +98,7 @@ class ScoperExprVisitor(ScoperVisitor):
             node.is_await = True
             actual = actual.return_type.resolve()
 
-            if isinstance(actual, Promise) and actual.kind == PromiseKind.FORKED \
+            if self.scope.function and isinstance(actual, Promise) and actual.kind == PromiseKind.FORKED \
                     and isinstance(fty := self.scope.function.obj_type.return_type, Promise):
                 fty.kind = PromiseKind.JOIN