_result_types grows unbounded for unanswered requests

[meymchen]

Component

pygls/protocol/json_rpc.py

Summary

For every outgoing request, _result_types[msg_id] is populated but only removed when a response is received. If the remote peer never responds (due to timeout, crash, or network loss), the entry leaks indefinitely.

Steps to Reproduce

1. Send a request to a peer that will never answer.
2. _result_types retains the mapping forever.

Expected Behavior

Entries should be cleaned up when the corresponding future is cancelled or garbage-collected.

Actual Behavior

Memory leak for every unanswered request.

Affected Code (pygls/protocol/json_rpc.py, ~L697-698)

self._request_futures[msg_id] = future
self._result_types[msg_id] = self.get_result_type(method)

Proposed Fix

Add a done-callback to future that pops the _result_types entry even when no response arrives.