Fix mypy on latest Twisted release (#17036)

`ITransport.abortConnection` isn't a thing, but
`HTTPChannel.forceAbortClient` calls it, so lets just use that

Fixes https://github.com/element-hq/synapse/issues/16728

1 files changed, 2 insertions, 2 deletions

diff --git a/synapse/http/server.py b/synapse/http/server.py

index 632284712c..c76500e14f 100644
--- a/synapse/http/server.py
+++ b/synapse/http/server.py
@@ -153,9 +153,9 @@ def return_json_error(
     # Only respond with an error response if we haven't already started writing,
     # otherwise lets just kill the connection
     if request.startedWriting:
-        if request.transport:
+        if request.channel:
             try:
-                request.transport.abortConnection()
+                request.channel.forceAbortClient()
             except Exception:
                 # abortConnection throws if the connection is already closed
                 pass