fix: fix crash after shift+delete (#84)

CHANGELOG.md

@@ -4,6 +4,10 @@ All notable changes to this project will be documented in this file.
 
 ## [Unreleased]
 
+### Bug Fixes
+
+-   Fixes a crash caused by <kbd>shift+delete</kbd> on a buffer with only one line.
+
 ## [0.5.0] - 2023-08-22
 
 ### Features

src/textual_textarea/textarea.py

@@ -406,14 +406,18 @@ def on_key(self, event: events.Key) -> None:
             if selection_before is None:
                 # delete whole line
                 cursor_before = self.cursor
-                if self.cursor.lno == len(self.lines) - 1:
-                    self.cursor = Cursor(lno=self.cursor.lno - 1, pos=0)
+                if len(self.lines) > 1:
+                    if self.cursor.lno == len(self.lines) - 1:
+                        self.cursor = Cursor(lno=self.cursor.lno - 1, pos=0)
+                    else:
+                        self.cursor = Cursor(lno=self.cursor.lno, pos=0)
+                    self.lines = (
+                        self.lines[0 : cursor_before.lno]
+                        + self.lines[cursor_before.lno + 1 :]
+                    )
                 else:
-                    self.cursor = Cursor(lno=self.cursor.lno, pos=0)
-                self.lines = (
-                    self.lines[0 : cursor_before.lno]
-                    + self.lines[cursor_before.lno + 1 :]
-                )
+                    self.lines = [" "]
+                    self.cursor = Cursor(0, 0)
             else:
                 # delete selection, same as plain delete
                 self._delete_selection(selection_before, self.cursor)

tests/functional_tests/test_textarea.py

@@ -126,6 +126,15 @@
             None,
             Cursor(2, 0),
         ),
+        (
+            ["shift+delete"],
+            ["foo "],
+            None,
+            Cursor(3, 1),
+            [" "],
+            None,
+            Cursor(0, 0),
+        ),
     ],
 )
 @pytest.mark.asyncio