Remove unused internal code

src/flask/cli.py

@@ -687,14 +687,6 @@ class FlaskGroup(AppGroup):
 
         return super().parse_args(ctx, args)
 
-
-def _path_is_ancestor(path: str, other: str) -> bool:
-    """Take ``other`` and remove the length of ``path`` from it. Then join it
-    to ``path``. If it is the original value, ``path`` is an ancestor of
-    ``other``."""
-    return os.path.join(path, other[len(path) :].lstrip(os.sep)) == other
-
-
 def load_dotenv(
     path: str | os.PathLike[str] | None = None, load_defaults: bool = True
 ) -> bool:

src/flask/debughelpers.py

@@ -14,12 +14,6 @@ if t.TYPE_CHECKING:
     from .wrappers import Request
 
 
-class UnexpectedUnicodeError(AssertionError, UnicodeError):
-    """Raised in places where we want some better error reporting for
-    unexpected unicode or binary data.
-    """
-
-
 class DebugFilesKeyError(KeyError, AssertionError):
     """Raised from request.files during debugging.  The idea is that it can
     provide a better error message than just a generic KeyError/BadRequest.