Update mtdna_backend.py

mtdna_backend.py

@@ -312,9 +312,20 @@ def summarize_results(accession, stop_flag=None):
 
         # ✅ Read existing data
         existing_data = sheet.get_all_values()
+    
         if existing_data:
             df_old = pd.DataFrame(existing_data[1:], columns=existing_data[0])
         else:
+            required_columns = [
+            "Sample ID", "Actual_country", "Actual_sample_type", "Country Explanation",
+            "Match_country", "Match_sample_type", "Predicted Country", "Predicted Sample Type",
+            "Query_cost", "Sample Type Explanation", "Sources", "Time cost", "file_chunk", "file_all_output"
+            ]
+            
+            for col in required_columns:
+                if col not in df_old.columns:
+                    df_old[col] = ""  # create empty column
+
             df_old = pd.DataFrame(columns=[
                 "Sample ID", "Actual_country", "Actual_sample_type", "Country Explanation",
                 "Match_country", "Match_sample_type", "Predicted Country", "Predicted Sample Type",