Impossible to access an attribute (\"flashbag\") on a null variable

[mdogancay]

{"code":500,"error":"Impossible to access an attribute (\"flashbag\") on a null variable.","ex":"{\"file:\":\"/***********/vendor/jmose/command-scheduler-bundle/Resources/views/layout.html.twig\",\"line\":22,\"previous\":null}","exec_time":0.012557029724121094}

i got this error on getting
http://localhost:8000/command-scheduler/list
on symfony serve command with development server.

It's about sessions.

I don't wanna use the session. This is an custom jwt api even i don't need sessions.
So any ideas the fix this?