How can I be sure this local variable is set after switch statement?

I have a scenario in my code where PhpStorm alerts me that a local variable $offers may be undefined. You can find the code scenario below as well as the alert from the IDE. Is intellisense right or wrong? The local variable is set regardless of the case as far as I can see.

Code:

function checkProduct($product, $retailerId){
    switch (isTokenValid(getBearerToken())){
        case true:
            $offers = getOffers($product, getBearerToken());
            break;
        case false:
            requestBearerToken();
            $offers = getOffers($product, getBearerToken());
            break;
    }
  if(!isBestOfferOurs($offers)){
    alertRetailer($product);
  }
}

EDIT:
replacing the false case to a default seems to resolve the issue and this ensures that $offers is always set.

        case true:
            $offers = getOffers($product, getBearerToken());
            break;
        default:
            requestBearerToken();
            $offers = getOffers($product, getBearerToken());
    }```
Alert:

[![php alert][1]][1]


  [1]: https://i.stack.imgur.com/Y7zVc.png

>Solution :

You can either preset the variable at the beginning of your function to an empty value, or you could add a default case to your switch statement below the false case. Either of those should satisfy your IDE.

Even though PHP switch statements do a loose type comparison (https://www.php.net/manual/en/control-structures.switch.php), PhpStorm doesn’t seem to know that and thinks that there could be a value that isn’t satisfied by your switch statement (which is why I suggested adding a default case). So it’s technically wrong.