lib.App: Allow _run() without subcommands

Overriding the _run() method entirely in App subclasses is currently only possible if the application supports a subcommand structure. Make it possible to use it as an abstraction for a single-command application.
Signed-off-by: Jan Lindemann <jan@janware.com>

src/python/jw/pkg/lib/App.py

@@ -199,10 +199,6 @@ class App:  # export
 
         exit_status = 0
 
-        if not hasattr(self.__args, 'func'):
-            self.__parser.print_help()
-            return None
-
         pr = None if self.__args.write_profile is None else cProfile.Profile()
         if pr is not None:
             pr.enable()
@@ -231,8 +227,14 @@ class App:  # export
         if exit_status:
             sys.exit(exit_status)
 
-    # Run sub-command. Overwrite if you want to do anything before or after
+    # Do the main work. Tries to run sub-commands by default. Overwrite if you
+    # want to do something else, for instance if you don't have sub-commands,
+    # or if want to do anything before and / or after the subcommands.
     async def _run(self, args: Namespace) -> None | int:
+        if not hasattr(self.__args, 'func'):
+            self.__parser.print_help()
+            return None
+        # Run sub-command. Overwrite if you want to do anything before or after
         return await self.args.func(args)
 
     def call_async(self, awaitable: Awaitable[T], timeout: float | None = None) -> T: