Fix reporting of server-side errors in "bw sync". (#6855)

Co-authored-by: SmithThe4th <gsmith@bitwarden.com>

libs/common/src/services/api.service.ts

@@ -1948,7 +1948,6 @@ export class ApiService implements ApiServiceAbstraction {
           responseJson.error === "invalid_grant")
       ) {
         await this.logoutCallback("invalidGrantError");
-        return null;
       }
     }