fix: catch failing external resouce: huggingface dataset

- this version includes a data mock, since downstream processing
assumes everything worked. one step at a time

src/maps/obs_map.py

@@ -3,6 +3,10 @@ import logging
 
 import pandas as pd
 from datasets import load_dataset
+from datasets import DatasetDict, Dataset
+
+import time
+
 import streamlit as st
 import folium
 from streamlit_folium import st_folium
@@ -113,6 +117,33 @@ def create_map(tile_name:str, location:Tuple[float], zoom_start: int = 7) -> fol
     #folium.LayerControl().add_to(m)
     return m
 
+def try_download_dataset(dataset_id:str, data_files:str, mockdata_on_failure:bool=False) -> dict:
+    # the `mockdata_on_failure` generates a minimal compliant dataset if the download fails
+    # (one step at a time)
+    t1 = time.time()
+    try:
+        m_logger.info(f"Starting to download dataset {dataset_id} from Hugging Face")
+        metadata:DatasetDict = load_dataset(dataset_id, data_files=data_files)
+        t2 = time.time(); elap = t2 - t1
+    except Exception as e:
+        t2 = time.time(); elap = t2 - t1
+        msg = f"Error downloading dataset: {e}.  (after {elap:.2f}s) Using mock data to continue"
+        st.error(msg)
+        m_logger.error(msg)
+        if mockdata_on_failure:
+            metadata = {'train':
+                         {'latitude': [0],
+                          'longitude': [0],
+                          'predicted_class': ['rough_toothed_dolphin']}
+                       }
+
+        else:
+            metadata = {}
+
+    msg = f"Downloaded dataset: (after {elap:.2f}s). "
+    m_logger.info(msg)
+    st.write(msg)
+    return metadata
 
 
 def present_obs_map(dataset_id:str = "Saving-Willy/Happywhale-kaggle",
@@ -139,7 +170,7 @@ def present_obs_map(dataset_id:str = "Saving-Willy/Happywhale-kaggle",
     """
 
     # load/download data from huggingface dataset
-    metadata = load_dataset(dataset_id, data_files=data_files)
+    metadata = try_download_dataset(dataset_id, data_files, mockdata_on_failure=True)   
     
     # make a pandas df that is compliant with folium/streamlit maps
     _df = pd.DataFrame({