Add error handling for data loading and plot generation

app.py

@@ -251,7 +251,11 @@ def format_instruction_html(text: str) -> str:
 
 def build_interface():
     """Build Gradio interface."""
-    metadata, end_effector, hands_2d = load_data()
+    try:
+        metadata, end_effector, hands_2d = load_data()
+    except Exception as e:
+        print(f"Error loading data: {e}")
+        metadata, end_effector, hands_2d = {}, {}, {}
     
     total_frames = len(metadata.get('poses', []))
     fps = metadata.get('fps', 60)
@@ -262,13 +266,23 @@ def build_interface():
     
     video_path = get_data_dir() / "video.mp4"
     
-    # Build data for left hand
-    left_timestamps, left_state = build_state_dataframe(metadata, end_effector, "left")
-    left_figs = {metric: build_plot_html(left_timestamps, left_state, metric) for metric in METRIC_LABELS.keys()}
+    # Build data for left hand (lazy - only if needed)
+    left_figs = {}
+    right_figs = {}
+    try:
+        left_timestamps, left_state = build_state_dataframe(metadata, end_effector, "left")
+        left_figs = {metric: build_plot_html(left_timestamps, left_state, metric) for metric in METRIC_LABELS.keys()}
+    except Exception as e:
+        print(f"Error building left plots: {e}")
+        left_figs = {metric: "<p>Plot unavailable</p>" for metric in METRIC_LABELS.keys()}
     
     # Build data for right hand
-    right_timestamps, right_state = build_state_dataframe(metadata, end_effector, "right")
-    right_figs = {metric: build_plot_html(right_timestamps, right_state, metric) for metric in METRIC_LABELS.keys()}
+    try:
+        right_timestamps, right_state = build_state_dataframe(metadata, end_effector, "right")
+        right_figs = {metric: build_plot_html(right_timestamps, right_state, metric) for metric in METRIC_LABELS.keys()}
+    except Exception as e:
+        print(f"Error building right plots: {e}")
+        right_figs = {metric: "<p>Plot unavailable</p>" for metric in METRIC_LABELS.keys()}
     
     stats_html = f"""
 <div class="stats-card">