Minor Fixes.

I'm investigating an issue where Jupyter-Console does not and it seem
there are mixup between sync and async KernelManager and other in a few
places.

Basically both Async and Blocking KM are expected by the type system to
work as KM independently, but obviously some have Async methods and
other have Sync methods, which need to be awaited.

When touching traitlets config files it's easy to change the default
class from Sync to async, and then you get weird error messages.

So dropping a few asserts here and fixign a few types while
investigating.

I think the Sync and Async should be more distinct now that we are
mostly async everywhere to avoid those confusions.

jupyter_client/consoleapp.py

@@ -13,6 +13,7 @@
 import typing as t
 import uuid
 import warnings
+from inspect import iscoroutinefunction
 
 from jupyter_core.application import base_aliases, base_flags
 from traitlets import CBool, CUnicode, Dict, List, Type, Unicode
@@ -149,7 +150,7 @@ def _connection_file_default(self) -> str:
         to force a direct exit without any confirmation.""",
     )
 
-    def build_kernel_argv(self, argv: object = None) -> None:
+    def build_kernel_argv(self, argv: t.Any = None) -> None:
         """build argv to be passed to kernel subprocess
 
         Override in subclasses if any args should be passed to the kernel
@@ -311,6 +312,8 @@ def init_kernel_manager(self) -> None:
             self.exit(1)  # type:ignore[attr-defined]
 
         self.kernel_manager = t.cast(KernelManager, self.kernel_manager)
+
+        assert not iscoroutinefunction(self.kernel_manager.start_kernel)
         self.kernel_manager.client_factory = self.kernel_client_class
         kwargs = {}
         kwargs["extra_arguments"] = self.kernel_argv
@@ -352,7 +355,7 @@ def init_kernel_client(self) -> None:
 
         self.kernel_client.start_channels()
 
-    def initialize(self, argv: object = None) -> None:
+    def initialize(self, argv: t.Any = None) -> None:
         """
         Classes which mix this class in should call:
                JupyterConsoleApp.initialize(self,argv)