Catch errors from external service and display in alert box

Closes: #129

agenda/data.py

@@ -276,12 +276,15 @@ async def time_function(
     func: typing.Callable[..., typing.Coroutine[typing.Any, typing.Any, typing.Any]],
     *args,
     **kwargs,
-) -> tuple[str, typing.Any, float]:
+) -> tuple[str, typing.Any, float, Exception | None]:
     """Time the execution of an asynchronous function."""
-    start_time = time()
-    result = await func(*args, **kwargs)
+    start_time, result, exception = time(), None, None
+    try:
+        result = await func(*args, **kwargs)
+    except Exception as e:
+        exception = e
     end_time = time()
-    return name, result, end_time - start_time
+    return name, result, end_time - start_time, exception
 
 
 def gap_list(
@@ -344,6 +347,8 @@ async def get_data(
 
     results = {call[0]: call[1] for call in result_list}
 
+    errors = [(call[0], call[3]) for call in result_list if call[3]]
+
     gwr_advance_tickets = results["gwr_advance_tickets"]
 
     data_gather_seconds = time() - t0
@@ -389,7 +394,9 @@ async def get_data(
     events += accommodation_events
     events += travel.all_events(my_data)
     events += conference.get_list(os.path.join(my_data, "conferences.yaml"))
-    events += results["backwell_bins"] + results["bristol_bins"]
+    for key in "backwell_bins", "bristol_bins":
+        if results[key]:
+            events += results[key]
     events += read_events_yaml(my_data, last_year, next_year)
     events += subscription.get_events(os.path.join(my_data, "subscriptions.yaml"))
     events += economist.publication_dates(last_week, next_year)
@@ -467,5 +474,6 @@ async def get_data(
     reply["two_weeks_ago"] = two_weeks_ago
 
     reply["fullcalendar_events"] = calendar.build_events(events)
+    reply["errors"] = errors
 
     return reply

templates/index.html

@@ -127,6 +127,14 @@
     Sunset: {{ sunset.strftime("%H:%M:%S") }}</li>
     </ul>
 
+  {% if errors %}
+    {% for error in errors %}
+      <div class="alert alert-danger" role="alert">
+        Error: {{ error }}
+      </div>
+    {% endfor %}
+  {% endif %}
+
   <h3>Stock markets</h3>
   {% for market in stock_markets %}
     <p>{{ market }}</p>