ArchLinux patch for Python 3.8 compatibility:
https://git.archlinux.org/svntogit/community.git/tree/trunk/python-3.8.patch?h=packages/python-jsonrpc-server

see also upstream PR: https://github.com/palantir/python-jsonrpc-server/pull/37

--- pyls_jsonrpc/endpoint.py.orig	2020-05-09 12:05:24.000000000 -0400
+++ pyls_jsonrpc/endpoint.py	2020-05-09 12:06:40.000000000 -0400
@@ -98,7 +98,7 @@
             message (dict): The JSON RPC message sent by the client
         """
         if 'jsonrpc' not in message or message['jsonrpc'] != JSONRPC_VERSION:
-            log.warn("Unknown message type %s", message)
+            log.warning("Unknown message type %s", message)
             return

         if 'id' not in message:
@@ -135,7 +135,7 @@
         try:
             handler = self._dispatcher[method]
         except KeyError:
-            log.warn("Ignoring notification for unknown method %s", method)
+            log.warning("Ignoring notification for unknown method %s", method)
             return

         try:
@@ -165,7 +165,7 @@
         request_future = self._client_request_futures.pop(msg_id, None)

         if not request_future:
-            log.warn("Received cancel notification for unknown message id %s", msg_id)
+            log.warning("Received cancel notification for unknown message id %s", msg_id)
             return

         # Will only work if the request hasn't started executing
@@ -230,12 +230,13 @@
         request_future = self._server_request_futures.pop(msg_id, None)

         if not request_future:
-            log.warn("Received response to unknown message id %s", msg_id)
+            log.warning("Received response to unknown message id %s", msg_id)
             return

         if error is not None:
             log.debug("Received error response to message %s: %s", msg_id, error)
             request_future.set_exception(JsonRpcException.from_dict(error))
+            return

         log.debug("Received result for message %s: %s", msg_id, result)
         request_future.set_result(result)
--- test/test_endpoint.py.orig	2020-05-09 12:07:34.000000000 -0400
+++ test/test_endpoint.py	2020-05-09 12:08:18.000000000 -0400
@@ -115,9 +115,9 @@
         'params': {'id': MSG_ID}
     })

-    with pytest.raises(exceptions.JsonRpcException) as exc_info:
+    with pytest.raises((exceptions.JsonRpcException, futures.CancelledError)) as exc_info:
         assert future.result(timeout=2)
-    assert exc_info.type == exceptions.JsonRpcRequestCancelled
+    assert exc_info.type in (exceptions.JsonRpcRequestCancelled, futures.CancelledError)


 def test_consume_notification(endpoint, dispatcher):