get app name from function

pywebio/output.py

@@ -1907,7 +1907,7 @@ def popup(title: str, content: Union[str, Output, List[Union[str, Output]]] = No
         When set to ``False``, the popup window can only be closed by :func:`popup_close()`,
         at this time the ``implicit_close`` parameter will be ignored.
 
-    ``popup()`` can be used in 3 ways: direct call, context manager, and decorator.
+    ``popup()`` can be used in 2 ways: direct call and context manager.
 
     * direct call:
 

pywebio/platform/page.py

@@ -78,6 +78,9 @@ def parse_app_metadata(func):
     else:
         title, description = parts[0], ''
 
+    if not title:
+        title = get_function_name(func)
+
     if not meta.title:
         meta = meta._replace(title=title, description=description)