update app.py

app.py

@@ -369,9 +369,11 @@ def calculate_custom_formula(image, geometry, selected_bands, custom_formula, re
         # Check if all selected bands are available in the image
         missing_bands = [band for band in selected_bands if band not in band_names]
         if missing_bands:
-            st.warning(f"The following bands are not available in the dataset for this image: {', '.join(missing_bands)}. Available bands: {', '.join(band_names)}. Please adjust your formula or data selection.")
-            return ee.Image(0).rename('custom_result').set('error', f"Missing bands: {', '.join(missing_bands)}")
+            error_msg = f"The following bands are not available in this image: {', '.join(missing_bands)}. Available bands: {', '.join(band_names)}. Please adjust your formula or check the data for your region and date range."
+            st.error(error_msg)
+            return ee.Image(0).rename('custom_result').set('error', error_msg)
 
+        # Only proceed if all bands are available
         for band in selected_bands:
             band_values[band] = image.select(band)