control reaches end of non-void function about pubsubclient HOT 1 OPEN

Ditto for me on ESP-8266 , the code worked originally so I am assume PIO (especially compiler: Core 6.1.4 Home 3.4.3) updates make this more stringent? Is this as straight forward as rewriting the function to read?:

 message_type Publish::response_type(void) const {
    switch (qos()) {
    case 1:
      return PUBACK;
    case 2:
      return PUBREC;
    default:
      return None;
    }
  }

Obviously compiles etc., but any unwanted side effects? I note the case indices do not relate to the enum order in any event, since that reads:

None=0
PUBACK=4
PUBREC=5

Seems then a safe fix?

Relevant platformio.ini:

[env:d1_mini]
platform = espressif8266
board = d1_mini
framework = arduino

I note there are a range of warnings of same but less lethal ilk?

from pubsubclient.