Handle BrokenPipeError gracefully when client disconnects during response

[Copilot]

When clients disconnect mid-response, BrokenPipeError cascades through wsgiref's error handlers, producing confusing multi-exception tracebacks with TypeError and AttributeError as the handler tries to send error responses over a closed connection.

Changes

• Catch connection errors at response send: Added exception handler in Application.__request__() for BrokenPipeError, ConnectionResetError, and ConnectionAbortedError when calling response(start_response). Returns empty iterable to cleanly terminate WSGI cycle.

• Log as info, not error: Client disconnections are expected behavior. Changed from implicit error-level cascading tracebacks to single log.info() message.

try:
    return response(start_response)
except (BrokenPipeError, ConnectionResetError, ConnectionAbortedError) as err:
    log.info("Client disconnected: %s", str(err))
    return ()

This mirrors the existing ConnectionError handling during request processing, but applies to the response phase where wsgiref's own error handling would otherwise fail.

Original prompt

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This section details on the original issue you should resolve

<issue_title>BrokenPipe ... better output</issue_title>
<issue_description>```
ERROR: Error for client 10.24.223.248 {handle_error():17}
#012Traceback (most recent call last):
#12 File "/usr/lib/python3.7/wsgiref/handlers.py", line 138, in run
#12 self.finish_response()
#12 File "/usr/lib/python3.7/wsgiref/handlers.py", line 180, in finish_response
#12 self.write(data)
#12 File "/usr/lib/python3.7/wsgiref/handlers.py", line 274, in write
#12 self.send_headers()
#12 File "/usr/lib/python3.7/wsgiref/handlers.py", line 332, in send_headers
#12 self.send_preamble()
#12 File "/usr/lib/python3.7/wsgiref/handlers.py", line 255, in send_preamble
#12 ('Date: %s\r\n' % format_date_time(time.time())).encode('iso-8859-1')
#12 File "/usr/lib/python3.7/wsgiref/handlers.py", line 453, in _write
#12 result = self.stdout.write(data)
#12 File "/usr/lib/python3.7/socketserver.py", line 799, in write
#12 self._sock.sendall(b)
#012BrokenPipeError: [Errno 32] Broken pipe
#12
#012During handling of the above exception, another exception occurred:
#12
#012Traceback (most recent call last):
#12 File "/usr/lib/python3.7/wsgiref/handlers.py", line 141, in run
#12 self.handle_error()
#12 File "/usr/lib/python3.7/wsgiref/handlers.py", line 368, in handle_error
#12 self.finish_response()
#12 File "/usr/lib/python3.7/wsgiref/handlers.py", line 180, in finish_response
#12 self.write(data)
#12 File "/usr/lib/python3.7/wsgiref/handlers.py", line 274, in write
#12 self.send_headers()
#12 File "/usr/lib/python3.7/wsgiref/handlers.py", line 331, in send_headers
#12 if not self.origin_server or self.client_is_modern():
#12 File "/usr/lib/python3.7/wsgiref/handlers.py", line 344, in client_is_modern
#12 return self.environ['SERVER_PROTOCOL'].upper() != 'HTTP/0.9'
#012TypeError: 'NoneType' object is not subscriptable
#12
#012During handling of the above exception, another exception occurred:
#12
#012Traceback (most recent call last):
#12 File "/usr/lib/python3.7/socketserver.py", line 650, in process_request_thread
#12 self.finish_request(request, client_address)
#12 File "/usr/lib/python3.7/socketserver.py", line 360, in finish_request
#12 self.RequestHandlerClass(request, client_address, self)
#12 File "/usr/lib/python3.7/socketserver.py", line 720, in init
#12 self.handle()
#12 File "/usr/lib/python3.7/wsgiref/simple_server.py", line 133, in handle
#12 handler.run(self.server.get_app())
#12 File "/usr/lib/python3.7/wsgiref/handlers.py", line 144, in run
#12 self.close()
#12 File "/usr/lib/python3.7/wsgiref/simple_server.py", line 35, in close
#12 self.status.split(' ',1)[0], self.bytes_sent
#012AttributeError: 'NoneType' object has no attribute 'split'

<agent_instructions>Check, if there is some possibility to handle BrokenPipeError better than this error log shows. BrokenPipeError happen, when client close connection while or before server response.</agent_instructions>

## Comments on the Issue (you are @copilot in this section)

<comments>
</comments>

• Fixes BrokenPipe ... better output #19

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