move no cover to dynamic key default

Author: rmorshea

src/idom/core/layout.py

@@ -684,7 +684,7 @@ def _process_child_type_and_key(
             key = None
 
         if key is None:
-            key = _default_key(index)
+            key = index
 
         yield (child, child_type, key)
 
@@ -698,10 +698,10 @@ def _process_child_type_and_key(
 
 if IDOM_FEATURE_INDEX_AS_DEFAULT_KEY.current:
 
-    def _default_key(index: int) -> Any:  # pragma: no cover
+    def _default_key(index: int) -> Any:
         return index
 
 else:
 
-    def _default_key(index: int) -> Any:
+    def _default_key(index: int) -> Any:  # pragma: no cover
         return object()