Avoid decoding jwt twice

Currently the Session::authenticate() function (which runs on every request and consumes CPU cycles) is decoding the jwt twice unnecessarily. This small refactor fixes that

Author: na-ka-na

workos/session.py

@@ -77,20 +77,20 @@ def authenticate(
                 reason=AuthenticateWithSessionCookieFailureReason.INVALID_SESSION_COOKIE,
             )
 
-        if not self._is_valid_jwt(session["access_token"]):
+        try:
+            signing_key = self.jwks.get_signing_key_from_jwt(session["access_token"])
+            decoded = jwt.decode(
+                token,
+                signing_key.key,
+                algorithms=self.jwk_algorithms,
+                options={"verify_aud": False},
+            )
+        except jwt.exceptions.InvalidTokenError:
             return AuthenticateWithSessionCookieErrorResponse(
                 authenticated=False,
                 reason=AuthenticateWithSessionCookieFailureReason.INVALID_JWT,
             )
 
-        signing_key = self.jwks.get_signing_key_from_jwt(session["access_token"])
-        decoded = jwt.decode(
-            session["access_token"],
-            signing_key.key,
-            algorithms=self.jwk_algorithms,
-            options={"verify_aud": False},
-        )
-
         return AuthenticateWithSessionCookieSuccessResponse(
             authenticated=True,
             session_id=decoded["sid"],
@@ -128,19 +128,6 @@ def get_logout_url(self, return_to: Optional[str] = None) -> str:
         )
         return str(result)
 
-    def _is_valid_jwt(self, token: str) -> bool:
-        try:
-            signing_key = self.jwks.get_signing_key_from_jwt(token)
-            jwt.decode(
-                token,
-                signing_key.key,
-                algorithms=self.jwk_algorithms,
-                options={"verify_aud": False},
-            )
-            return True
-        except jwt.exceptions.InvalidTokenError:
-            return False
-
     @staticmethod
     def seal_data(data: Dict[str, Any], key: str) -> str:
         fernet = Fernet(key)