hardening

src/textual/app.py

@@ -2617,9 +2617,14 @@ async def recompose(self) -> None:
 
         Recomposing will remove children and call `self.compose` again to remount.
         """
-        async with self.screen.batch():
-            await self.screen.query("*").exclude(".-textual-system").remove()
-            await self.screen.mount_all(compose(self))
+        if self._exit:
+            return
+        try:
+            async with self.screen.batch():
+                await self.screen.query("*").exclude(".-textual-system").remove()
+                await self.screen.mount_all(compose(self))
+        except ScreenStackError:
+            pass
 
     def _register_child(
         self, parent: DOMNode, child: Widget, before: int | None, after: int | None

src/textual/widget.py

@@ -1005,6 +1005,8 @@ def mount_all(
             Only one of ``before`` or ``after`` can be provided. If both are
             provided a ``MountError`` will be raised.
         """
+        if self.app._exit:
+            return AwaitMount(self, [])
         await_mount = self.mount(*widgets, before=before, after=after)
         return await_mount
 

src/textual/widgets/_header.py

@@ -7,6 +7,7 @@
 from rich.text import Text
 
 from ..app import RenderResult
+from ..dom import NoScreen
 from ..events import Click, Mount
 from ..reactive import Reactive
 from ..widget import Widget
@@ -213,10 +214,16 @@ def screen_sub_title(self) -> str:
 
     def _on_mount(self, _: Mount) -> None:
         async def set_title() -> None:
-            self.query_one(HeaderTitle).text = self.screen_title
+            try:
+                self.query_one(HeaderTitle).text = self.screen_title
+            except NoScreen:
+                pass
 
         async def set_sub_title() -> None:
-            self.query_one(HeaderTitle).sub_text = self.screen_sub_title
+            try:
+                self.query_one(HeaderTitle).sub_text = self.screen_sub_title
+            except NoScreen:
+                pass
 
         self.watch(self.app, "title", set_title)
         self.watch(self.app, "sub_title", set_sub_title)