only run early 404 exit if it is not an async page builder

Author: rodja

nicegui/elements/sub_pages.py

@@ -108,11 +108,12 @@ def _render_page(self, match: RouteMatch) -> bool:
             self._render_error(e)
             return True
 
-        # NOTE: if the full path could not be consumed, the deepest sub pages element must handle the possible 404
-        if match.remaining_path and not any(isinstance(el, SubPages) for el in self.descendants()):
-            if asyncio.iscoroutine(result):
-                result.close()
-            return False
+        if not asyncio.iscoroutine(result):
+            # NOTE: if the full path could not be consumed, the deepest sub pages element must handle the possible 404
+            if match.remaining_path and not any(isinstance(el, SubPages) for el in self.descendants()):
+                if asyncio.iscoroutine(result):
+                    result.close()
+                return False
 
         self._handle_scrolling(match, behavior='instant')
         if asyncio.iscoroutine(result):