chore: move errors into core under the import catch block

asyncio/core.py

@@ -24,16 +24,24 @@
 except ImportError:
     from .task import TaskQueue, Task
 
+################################################################################
+# Exceptions
+
+
 # Depending on the release of CircuitPython these errors may or may not
 # exist in the C implementation of `_asyncio`.  However, when they
 # do exist, they must be preferred over the Python code.
 try:
     from _asyncio import CancelledError, InvalidStateError
 except (ImportError, AttributeError):
-    from .task import CancelledError, InvalidStateError
+    class CancelledError(BaseException):
+        """Injected into a task when calling `Task.cancel()`"""
+        pass
 
-################################################################################
-# Exceptions
+
+    class InvalidStateError(Exception):
+        """Can be raised in situations like setting a result value for a task object that already has a result value set."""
+        pass
 
 
 class TimeoutError(Exception):

asyncio/task.py

@@ -21,18 +21,6 @@
 from . import core
 
 
-class CancelledError(BaseException):
-    """Injected into a task when calling `Task.cancel()`"""
-
-    pass
-
-
-class InvalidStateError(Exception):
-    """Can be raised in situations like setting a result value for a task object that already has a result value set."""
-
-    pass
-
-
 # pairing-heap meld of 2 heaps; O(1)
 def ph_meld(h1, h2):
     if h1 is None: