email_password_sign_in_page exception

this error comes when I do a email password - signin or register
[it does log me in]
exception
E/flutter (22129): [ERROR:flutter/lib/ui/ui_dart_state.cc(157)] Unhandled Exception: Bad state: No element
[ ] E/flutter (22129): #0 List.last (dart:core-patch/growable_array.dart:227:5)
[ ] E/flutter (22129): #1 NavigatorState.pop (package:flutter/src/widgets/navigator.dart:2118:43)
[ ] E/flutter (22129): #2 _EmailPasswordSignInPageState._submit
(package:firebase_auth_demo_flutter/app/sign_in/email_password/email_password_sign_in_page.dart:80:20)
[ ] E/flutter (22129):
[ ] E/flutter (22129): #3 _InkResponseState._handleTap (package:flutter/src/material/ink_well.dart:706:14)
[ ] E/flutter (22129): #4 _InkResponseState.build. (package:flutter/src/material/ink_well.dart:789:36)
[ ] E/flutter (22129): #5 GestureRecognizer.invokeCallback (package:flutter/src/gestures/recognizer.dart:182:24)
[ ] E/flutter (22129): #6 TapGestureRecognizer.handleTapUp (package:flutter/src/gestures/tap.dart:486:11)
[ ] E/flutter (22129): #7 BaseTapGestureRecognizer._checkUp (package:flutter/src/gestures/tap.dart:264:5)
[ ] E/flutter (22129): #8 BaseTapGestureRecognizer.acceptGesture (package:flutter/src/gestures/tap.dart:236:7)
[ ] E/flutter (22129): #9 GestureArenaManager.sweep (package:flutter/src/gestures/arena.dart:156:27)
[ ] E/flutter (22129): #10 GestureBinding.handleEvent (package:flutter/src/gestures/binding.dart:222:20)
[ ] E/flutter (22129): #11 GestureBinding.dispatchEvent (package:flutter/src/gestures/binding.dart:198:22)
[ ] E/flutter (22129): #12 GestureBinding._handlePointerEvent (package:flutter/src/gestures/binding.dart:156:7)
[ ] E/flutter (22129): #13 GestureBinding._flushPointerEventQueue (package:flutter/src/gestures/binding.dart:102:7)
[ ] E/flutter (22129): #14 GestureBinding._handlePointerDataPacket (package:flutter/src/gestures/binding.dart:86:7)
[ ] E/flutter (22129): #15 _rootRunUnary (dart:async/zone.dart:1138:13)
[ ] E/flutter (22129): #16 _CustomZone.runUnary (dart:async/zone.dart:1031:19)
[ ] E/flutter (22129): #17 _CustomZone.runUnaryGuarded (dart:async/zone.dart:933:7)
[ ] E/flutter (22129): #18 _invoke1 (dart:ui/hooks.dart:273:10)
[ ] E/flutter (22129): #19 _dispatchPointerDataPacket (dart:ui/hooks.dart:182:5)
[ ] E/flutter (22129):

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Thank you