Fix for blanking bug

examples/code_viewer.py

@@ -1,7 +1,9 @@
 import os
 import sys
+from rich.console import RenderableType
 
 from rich.syntax import Syntax
+from rich.traceback import Traceback
 
 from textual import events
 from textual.app import App
@@ -12,9 +14,13 @@ class MyApp(App):
     """An example of a very simple Textual App"""
 
     async def on_load(self, event: events.Load) -> None:
+        """Sent before going in to application mode."""
+
+        # Bind our basic keys
         await self.bind("b", "view.toggle('sidebar')", "Toggle sidebar")
         await self.bind("q", "quit", "Quit")
 
+        # Get path to show
         try:
             self.path = sys.argv[1]
         except IndexError:
@@ -23,28 +29,43 @@ class MyApp(App):
             )
 
     async def on_mount(self, event: events.Mount) -> None:
+        """Call after terminal goes in to application mode"""
 
+        # Create our widgets
+        # In this a scroll view for the code and a directory tree
         self.body = ScrollView()
         self.directory = DirectoryTree(self.path, "Code")
 
+        # Dock our widgets
         await self.view.dock(Header(), edge="top")
         await self.view.dock(Footer(), edge="bottom")
+
+        # Note the directory is also in a scroll view
         await self.view.dock(
             ScrollView(self.directory), edge="left", size=32, name="sidebar"
         )
         await self.view.dock(self.body, edge="top")
 
     async def message_file_click(self, message: FileClick) -> None:
-        syntax = Syntax.from_path(
-            message.path,
-            line_numbers=True,
-            word_wrap=True,
-            indent_guides=True,
-            theme="monokai",
-        )
+        """A message sent by the directory tree when a file is clicked."""
+
+        syntax: RenderableType
+        try:
+            # Construct a Syntax object for the path in the message
+            syntax = Syntax.from_path(
+                message.path,
+                line_numbers=True,
+                word_wrap=True,
+                indent_guides=True,
+                theme="monokai",
+            )
+        except Exception:
+            # Possibly a binary file
+            # For demonstration purposes we will show the traceback
+            syntax = Traceback(theme="monokai", width=None, show_locals=True)
         self.app.sub_title = os.path.basename(message.path)
         await self.body.update(syntax)
-        self.body.home()
 
 
+# Run our app class
 MyApp.run(title="Code Viewer", log="textual.log")