Update app.py

app.py

@@ -894,13 +894,13 @@ input('Press Enter to exit...')""",
                     thread = threading.Thread(target=get_result)
                     thread.start()
                     
-                    # Progress simulation with log updates
+                    # Fixed: Progress simulation with proper string formatting
                     progress_steps = [
                         (0.1, "Checking Nuitka installation..."),
                         (0.15, "Checking MinGW-w64 for Windows targets..." if extension == ".exe" else "Checking environment..."),
                         (0.2, "Setting up environment..."),
                         (0.3, "Installing requirements..."),
-                        (0.4, f"Starting {"Windows cross-" if extension == ".exe" else ""}compilation..."),
+                        (0.4, f"Starting {'Windows cross-' if extension == '.exe' else ''}compilation..."),
                         (0.5, "Processing imports..."),
                         (0.6, "Optimizing code..."),
                         (0.7, f"Creating {extension} binary..."),