update

app.py

@@ -128,6 +128,7 @@ def introduction():
 def attribution():
     return render_template('attribution.html')
 
+
 @app.route('/index', methods=['GET', 'POST'])
 def index():
     if request.method == 'POST':
@@ -135,14 +136,14 @@ def index():
         seed = request.form.get('seed')
         method = request.form.get('method')
         if not username or not seed or not method:
-            return "Please fill in all fields and select a method.", 400
+            return render_template('index.html', error="Please fill in all fields and select a method.")
         try:
             seed = int(seed)
             random.seed(seed)
             all_samples = load_samples()
             selected_samples = select_balanced_samples(all_samples)
             if len(selected_samples) == 0:
-                return "No common samples were found", 500
+                return render_template('index.html', error="No common samples were found")
             start_time = datetime.now().isoformat()
             session_id = generate_session_id()
             session_data = {
@@ -159,9 +160,11 @@ def index():
             return redirect(url_for('explanation', session_id=session_id))
         except Exception as e:
             logger.exception(f"Error in index route: {e}")
-            return "An error occurred", 500
+            return render_template('index.html', error="An error occurred. Please try again.")
     return render_template('index.html')
 
+
+
 @app.route('/explanation/<session_id>')
 def explanation(session_id):
     session_data = session.get('data')