check for empty selection and return early if blank.

this fixes a crash should a draw be attempted without a selection.

pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "lottery-tui"
-version = "0.1.1"
+version = "0.2.1"
 description = "A terminal user interface for lottery games."
 authors = [{ name = "onyx-and-iris", email = "code@onyxandiris.online" }]
 dependencies = ["textual>=8.0.0"]
@@ -11,5 +11,13 @@ license = { text = "MIT" }
 [project.scripts]
 lottery-tui = "lottery_tui.tui:main"
 
+[build-system]
+requires = ["pdm-backend"]
+build-backend = "pdm.backend"
+
 [tool.pdm]
 distribution = true
+
+[tool.pdm.build]
+package-dir = "src"
+includes = ["src/**/*", "README.md", "LICENSE"]

src/lottery_tui/tui.py

@@ -37,11 +37,17 @@ class LotteryTUI(App):
     def on_button_pressed(self, event):
         """Handle button press events."""
         if event.button.id == 'draw-button':
+            if self.query_one('#lottery-select').is_blank():
+                self.query_one('#result-label').update(
+                    'Please select a lottery before drawing.'
+                )
+                return
+
             selected_lottery = self.query_one('#lottery-select').value
+
             try:
                 lottery_obj = request_lottery_obj(selected_lottery)
                 result = lottery_obj.draw()
-                self.query_one('#result-label').update(f'Result: {result}')
             except ValueError as e:
                 self.query_one('#result-label').update(str(e))