Flutter outputing JSNull Error when using auto-fill

[guitaristhk]

When I use auto fill-in to fill my username in the app, it pops the JSNull error. Has anyone been through this?

TypeError: null: type 'JSNull' is not a subtype of type 'String'

at Object.wrapException
(http://localhost:58580/dwds/src/injected/client.js:1249:43)
at Object._asString
(http://localhost:58580/dwds/src/injected/client.js:2840:15)
at main__closure7.call$1
(http://localhost:58580/dwds/src/injected/client.js:26677:54)
at _EventStreamSubscription_closure.call$1
(http://localhost:58580/dwds/src/injected/client.js:26040:26)
at StaticClosure._rootRunUnary
(http://localhost:58580/dwds/src/injected/client.js:4382:16)
at _CustomZone.runUnary$2$2
(http://localhost:58580/dwds/src/injected/client.js:14273:39)
at _CustomZone.runUnaryGuarded$1$2
(http://localhost:58580/dwds/src/injected/client.js:14220:14)
at _CustomZone_bindUnaryCallbackGuarded_closure.call$1
(http://localhost:58580/dwds/src/injected/client.js:14407:25)
at _callDartFunctionFast1
(http://localhost:58580/dwds/src/injected/client.js:7680:25)
at http://localhost:58580/dwds/src/injected/client.js:7656:18