Fix 'Unhandled error in Deferred' (#12089)

* Fix 'Unhandled error in Deferred'

Fixes a CRITICAL "Unhandled error in Deferred" log message which happened when
a function wrapped with `@cachedList` failed

* Minor optimisation to cachedListDescriptor

we can avoid re-using `missing`, which saves looking up entries in
`deferreds_map`, and means we don't need to copy it.

* Improve type annotation on CachedListDescriptor

1 files changed, 5 insertions, 5 deletions

diff --git a/tests/util/caches/test_descriptors.py b/tests/util/caches/test_descriptors.py
index b92d3f0c1b..19741ffcda 100644
--- a/tests/util/caches/test_descriptors.py
+++ b/tests/util/caches/test_descriptors.py
@@ -673,14 +673,14 @@ class CachedListDescriptorTestCase(unittest.TestCase):
             self.assertEqual(current_context(), SENTINEL_CONTEXT)
             r = yield d1
             self.assertEqual(current_context(), c1)
-            obj.mock.assert_called_once_with((10, 20), 2)
+            obj.mock.assert_called_once_with({10, 20}, 2)
             self.assertEqual(r, {10: "fish", 20: "chips"})
             obj.mock.reset_mock()
 
             # a call with different params should call the mock again
             obj.mock.return_value = {30: "peas"}
             r = yield obj.list_fn([20, 30], 2)
-            obj.mock.assert_called_once_with((30,), 2)
+            obj.mock.assert_called_once_with({30}, 2)
             self.assertEqual(r, {20: "chips", 30: "peas"})
             obj.mock.reset_mock()
 
@@ -701,7 +701,7 @@ class CachedListDescriptorTestCase(unittest.TestCase):
             obj.mock.return_value = {40: "gravy"}
             iterable = (x for x in [10, 40, 40])
             r = yield obj.list_fn(iterable, 2)
-            obj.mock.assert_called_once_with((40,), 2)
+            obj.mock.assert_called_once_with({40}, 2)
             self.assertEqual(r, {10: "fish", 40: "gravy"})
 
     def test_concurrent_lookups(self):
@@ -729,7 +729,7 @@ class CachedListDescriptorTestCase(unittest.TestCase):
         d3 = obj.list_fn([10])
 
         # the mock should have been called exactly once
-        obj.mock.assert_called_once_with((10,))
+        obj.mock.assert_called_once_with({10})
         obj.mock.reset_mock()
 
         # ... and none of the calls should yet be complete
@@ -771,7 +771,7 @@ class CachedListDescriptorTestCase(unittest.TestCase):
         # cache miss
         obj.mock.return_value = {10: "fish", 20: "chips"}
         r1 = yield obj.list_fn([10, 20], 2, on_invalidate=invalidate0)
-        obj.mock.assert_called_once_with((10, 20), 2)
+        obj.mock.assert_called_once_with({10, 20}, 2)
         self.assertEqual(r1, {10: "fish", 20: "chips"})
         obj.mock.reset_mock()