Fix empty paste.

Related issues: #2563.

CHANGELOG.md

@@ -20,6 +20,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 - Fixed `TreeNode.collapse` and `TreeNode.collapse_all` not posting a `Tree.NodeCollapsed` message https://github.com/Textualize/textual/issues/2535
 - Fixed `TreeNode.toggle` and `TreeNode.toggle_all` not posting a `Tree.NodeExpanded` or `Tree.NodeCollapsed` message https://github.com/Textualize/textual/issues/2535
 - `footer--description` component class was being ignored https://github.com/Textualize/textual/issues/2544
+- Pasting empty selection in `Input` would raise an exception https://github.com/Textualize/textual/issues/2563
 
 ### Added
 

src/textual/widgets/_input.py

@@ -332,7 +332,7 @@ class Input(Widget, can_focus=True):
             event.prevent_default()
 
     def _on_paste(self, event: events.Paste) -> None:
-        line = event.text.splitlines()[0]
+        line = event.text.splitlines()[0] if event.text else ""
         self.insert_text_at_cursor(line)
         event.stop()