fix: Raise more informative error instead of generic KeyError on end_stream

Author: joaquin-borggio-lc

src/h2/connection.py

@@ -919,10 +919,14 @@ def end_stream(self, stream_id: int) -> None:
  :param stream_id: The ID of the stream to end.
  :type stream_id: ``int``
  :returns: Nothing
+ :raises NoSuchStreamError: If the stream ID does not correspond to a
+ known stream and is higher than the current maximum stream ID.
+ :raises StreamClosedError: If the stream ID corresponds to a stream
+ that has been closed.
  """
  self.config.logger.debug("End stream ID %d", stream_id)
  self.state_machine.process_input(ConnectionInputs.SEND_DATA)
- frames = self.streams[stream_id].end_stream()
+ frames = self._get_stream_by_id(stream_id).end_stream()
  self._prepare_for_sending(frames)
 
  def increment_flow_control_window(self, increment: int, stream_id: int | None = None) -> None: