Define trio.Event.__bool__() to reduce bugs

src/trio/_sync.py

@@ -1,7 +1,7 @@
 from __future__ import annotations
 
 import math
-from typing import TYPE_CHECKING, Protocol
+from typing import TYPE_CHECKING, NoReturn, Protocol
 
 import attrs
 
@@ -112,6 +112,12 @@ def statistics(self) -> EventStatistics:
         """
         return EventStatistics(tasks_waiting=len(self._tasks))
 
+    def __bool__(self) -> NoReturn:
+        """Raise NotImplementedError."""
+        raise NotImplementedError(
+            "Trio events cannot be treated as bools; consider using 'event.is_set()'"
+        )
+
 
 class _HasAcquireRelease(Protocol):
     """Only classes with acquire() and release() can use the mixin's implementations."""