Handle tokens for deleted users

src/api/auth/jwt.py

@@ -2,6 +2,7 @@ from datetime import UTC, datetime, timedelta
 from enum import StrEnum
 from typing import Literal, NotRequired, TypedDict, cast, final
 
+from beanie import Link
 from jose import JWTError, jwt
 
 from src.db.models import user
@@ -34,6 +35,7 @@ class AuthErrState(StrEnum):
     EXPIRED = "The provided token is expired."
     UNTRACKED = "The provided token isn't tracked by the server"
     REVOKED = "The provided token was revoked"
+    NO_USER = "The provided token doesn't have a user linked to it"
 
 
 @final
@@ -123,6 +125,13 @@ async def resolve_jwt_token(token: str) -> tuple[TokenData, Token]:
     # We'll definitely end up needing the user, so we might as well fetch it now
     await db_token.fetch_link(Token.user)
 
+    # If we still get a link here, it means the user was deleted
+    # this shouldn't happen though, as with a user deletion, their tokens should
+    # also be deleted. Nevertheless, let's check it for sanity.
+    if isinstance(db_token.user, Link):
+        log.error(f"Got a token of a deleted user: {token=!r} user_id={db_token.user.ref.id!r}")
+        raise InvalidTokenError(AuthErrState.NO_USER, token)
+
     return decoded, db_token