Fix sorbet types of the jwt payload attr_reader

Author: BaggioGiacomo

lib/shopify_api/auth/jwt_payload.rb

@@ -10,11 +10,14 @@ class JwtPayload
       JWT_EXPIRATION_LEEWAY = JWT_LEEWAY
 
       sig { returns(String) }
-      attr_reader :iss, :dest, :aud, :sub, :jti, :sid
+      attr_reader :iss, :dest, :aud, :jti
 
       sig { returns(Integer) }
       attr_reader :exp, :nbf, :iat
 
+      sig { returns(T.nilable(String)) }
+      attr_reader :sub, :sid
+
       alias_method :expire_at, :exp
 
       sig { params(token: String).void }

lib/shopify_api/utils/session_utils.rb

@@ -49,7 +49,7 @@ def session_id_from_shopify_id_token(id_token:, online:)
           shop = payload.shop
 
           if online
-            jwt_session_id(shop, payload.sub)
+            jwt_session_id(shop, T.must(payload.sub))
           else
             offline_session_id(shop)
           end