anchor.diff:        try {
           token = TokenInfo.fromJson(json.decode(tokenJson) as Map<String, dynamic>);
         } on FormatException {
  +        log.warning('Failed to decode token JSON: $tokenJson');
           throw InternalServerError('Invalid JSON: "$tokenJson"');
         }
   
  
positive.code: 
        return AuthenticatedContext(agent: agent, clientContext: clientContext);
      } else if (swarmingToken != null) {
        return await authenticateAccessToken(swarmingToken, clientContext: clientContext, log: log);
      }
  
  
negative.code:         return AuthenticatedContext(clientContext: clientContext);
        }
  
        log.warning('${token.email} is not allowed');
        throw Unauthenticated('${token.email} is not allowed');
      } finally {
        client.close();
  