Data Persistence in Flutter

TypeError: Type error
    at toString (unknown)
    at onexitlabel (/app/lib/gsmlg_component-1.0.0/priv/server.js:72738:30)
    at compile2 (/app/lib/gsmlg_component-1.0.0/priv/server.js:72411:45)
    at Markdown (/app/lib/gsmlg_component-1.0.0/priv/server.js:74411:48)
    at renderWithHooks (/app/lib/gsmlg_component-1.0.0/priv/server.js:3894:40)
    at renderElement (/app/lib/gsmlg_component-1.0.0/priv/server.js:4050:38)
    at retryNode (/app/lib/gsmlg_component-1.0.0/priv/server.js:4412:382)
    at renderNodeDestructive (/app/lib/gsmlg_component-1.0.0/priv/server.js:4397:277)
    at renderNode (/app/lib/gsmlg_component-1.0.0/priv/server.js:4601:39)
    at renderElement (/app/lib/gsmlg_component-1.0.0/priv/server.js:4091:23)