Lazy load plot data to avoid module load errors

app.py

@@ -125,17 +125,25 @@ def prepare_data():
         'right_rot': right_rot
     }
 
-try:
-    plot_data = prepare_data()
-except Exception as e:
-    print(f"Error preparing plot data: {e}")
-    plot_data = {
-        'times': [],
-        'left_pos': {'x': [], 'y': [], 'z': []},
-        'left_rot': {'yaw': [], 'pitch': [], 'roll': []},
-        'right_pos': {'x': [], 'y': [], 'z': []},
-        'right_rot': {'yaw': [], 'pitch': [], 'roll': []}
-    }
+# Lazy load plot data
+plot_data = None
+
+def get_plot_data():
+    """Lazy load plot data."""
+    global plot_data
+    if plot_data is None:
+        try:
+            plot_data = prepare_data()
+        except Exception as e:
+            print(f"Error preparing plot data: {e}")
+            plot_data = {
+                'times': [],
+                'left_pos': {'x': [], 'y': [], 'z': []},
+                'left_rot': {'yaw': [], 'pitch': [], 'roll': []},
+                'right_pos': {'x': [], 'y': [], 'z': []},
+                'right_rot': {'yaw': [], 'pitch': [], 'roll': []}
+            }
+    return plot_data
 
 METRIC_LABELS = {
     "x_cm": "X (cm)",
@@ -255,40 +263,41 @@ CUSTOM_CSS = """
 def build_plot_fig(metric: str, hand: str = "left") -> go.Figure:
     """Build Plotly figure for a metric."""
     try:
-        times = plot_data.get('times', [])
+        data = get_plot_data()
+        times = data.get('times', [])
         
         if hand == "left":
             if "cm" in metric:
                 key = metric.replace('_cm', '')
-                data = plot_data.get('left_pos', {}).get(key, [])
+                plot_values = data.get('left_pos', {}).get(key, [])
             else:
                 key = metric.replace('_deg', '')
-                data = plot_data.get('left_rot', {}).get(key, [])
+                plot_values = data.get('left_rot', {}).get(key, [])
             name = "Left Hand"
         else:
             if "cm" in metric:
                 key = metric.replace('_cm', '')
-                data = plot_data.get('right_pos', {}).get(key, [])
+                plot_values = data.get('right_pos', {}).get(key, [])
             else:
                 key = metric.replace('_deg', '')
-                data = plot_data.get('right_rot', {}).get(key, [])
+                plot_values = data.get('right_rot', {}).get(key, [])
             name = "Right Hand"
         
-        if not times or not data:
+        if not times or not plot_values:
             # Return empty plot
             times = [0]
-            data = [0]
+            plot_values = [0]
     except Exception as e:
         print(f"Error in build_plot_fig: {e}")
         times = [0]
-        data = [0]
+        plot_values = [0]
         name = "Error"
     
     fig = go.Figure()
     fig.add_trace(
         go.Scatter(
             x=times,
-            y=data,
+            y=plot_values,
             mode="lines",
             name=name,
             line=dict(color="#67e8f9", width=2)