fix: handle EndOfStream and ClosedResourceError in send_request

Fixes #1717

The `send_request` method only catches `TimeoutError` from the
`response_stream_reader.receive()` call. If `receive()` raises
`EndOfStream` or `ClosedResourceError` (e.g., when the connection
closes unexpectedly), these exceptions propagate without being
caught, potentially leaving `response_or_error` unassigned and
causing an `UnboundLocalError` at the subsequent isinstance check.

This adds explicit handling for these stream closure exceptions,
converting them to `McpError` with `CONNECTION_CLOSED` error code.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: kxbnb

src/mcp/shared/session.py

@@ -280,6 +280,16 @@ async def send_request(
                         ),
                     )
                 )
+            except (anyio.EndOfStream, anyio.ClosedResourceError) as e:
+                raise McpError(
+                    ErrorData(
+                        code=CONNECTION_CLOSED,
+                        message=(
+                            f"Connection closed while waiting for response to "
+                            f"{request.__class__.__name__}: {e}"
+                        ),
+                    )
+                )
 
             if isinstance(response_or_error, JSONRPCError):
                 raise McpError(response_or_error.error)