ui: fix data missing issue

app.py

@@ -6,20 +6,43 @@ import pandas as pd
 import plotly.express as px
 
 
-def get_data():
+def get_data(*args, **kwargs):
     file_path = "predictions.json"
+    table_columns = ["Repository", "Language", "Trend Probability"]
+
     if not os.path.exists(file_path):
-        return pd.DataFrame(), "📅 Status: Waiting for data sync...", None
+        return (
+            pd.DataFrame(columns=table_columns),
+            "📅 Status: Waiting for data sync...",
+            None,
+        )
 
     try:
         with open(file_path, "r") as f:
-            raw_data = json.load(f)
+            # Handle empty file case
+            content = f.read()
+            if not content:
+                return (
+                    pd.DataFrame(columns=table_columns),
+                    "📅 Status: predictions.json is empty.",
+                    None,
+                )
+            raw_data = json.loads(content)
 
         predictions_list = raw_data.get("predictions", [])
         date = raw_data.get("prediction_date", "Unknown Date")
+        
+        # Handle case where 'predictions' key is missing or not a list
+        if not isinstance(predictions_list, list):
+             return (
+                pd.DataFrame(columns=table_columns),
+                f"### ⚠️ Error: 'predictions' format is invalid.",
+                None,
+            )
+        
         df = pd.DataFrame(predictions_list)
 
-        if not df.empty:
+        if not df.empty and all(col in df.columns for col in ['repo_name', 'language', 'probability']):
             # Sort for Chart (Ascending for horizontal Plotly layout)
             chart_df = df.sort_values(by="probability", ascending=True)
 
@@ -53,12 +76,22 @@ def get_data():
                 lambda x: f"{x:.1%}"
             )
             table_df = table_df[["repo_name", "language", "probability"]]
-            table_df.columns = ["Repository", "Language", "Trend Probability"]
+            table_df.columns = table_columns
 
             return table_df, f"### 📅 Last Prediction Run: {date}", fig
+        else:
+            return (
+                pd.DataFrame(columns=table_columns),
+                f"### 📅 Last Prediction Run: {date} (No valid data)",
+                None,
+            )
 
-    except Exception as e:
-        return pd.DataFrame({"Error": [str(e)]}), "### ⚠️ Error loading data", None
+    except (json.JSONDecodeError, Exception) as e:
+        return (
+            pd.DataFrame(columns=table_columns),
+            f"### ⚠️ Error loading data: {e}",
+            None,
+        )
 
 
 # CSS to center the markdown text since 'style' is no longer allowed in components