JSONDecodeError when trying to interact with user in a non-healthy server

We got a small federation running for Raiden Network, and because of some disk full issue, one of the servers crashed. Following it, the healthy ones started returning some unexpected responses for interactions with users on the healthy ones.
E.g. trying to invite an user in the unhealthy server to a room in the healthy one, the invite request returned:

<Response [429]>
{"errcode":"M_UNKNOWN","error":"Unknown Status"}

but from
https://github.com/matrix-org/matrix-python-sdk/blob/e366d52850f2bd948e9613022b735054616cfe0b/matrix_client/api.py#L731-L735
if the error isn't a json, json.JSONDecodeError will be raised.
Quick fix is to add json.JSONDecodeError to the handled errors in L734
Full stack traces and context can be found in raiden-network/raiden#2603

从 matrix_client/api.py 的 731–735 行附近开始，这里会解析并处理非 JSON 错误响应。重现包含所示错误负载的 429 响应，然后验证该交互遵循现有的已处理错误路径，而不会引发 JSONDecodeError。