Flutter web Instance of 'minified:eU<void>' - flutter

Question

I am building a Flutter web app, which runs flawlessly in debug mode, but whenever I try to run it in release mode or deploy it to the hosting I see a grey box.
I see this:
Instead of this:
As you may see, this is an alertDialog, here is the code of it:
class TeamDetailsDialog extends StatelessWidget {
final Tournament tournament;
final Team team;
final String matchId;
TeamDetailsDialog(this.team, this.matchId, this.tournament);
#override
Widget build(BuildContext context) {
return Theme(
data: ThemeData(buttonBarTheme: ButtonBarThemeData(alignment: MainAxisAlignment.spaceBetween)),
child: AlertDialog(
backgroundColor: Color(0xFF333D81),
title: Text(
"Csapatnév: ${team.name}",
style: TextStyle(color: Colors.white),
),
content: DefaultTextStyle(
style: TextStyle(color: Colors.white),
child: Column(
mainAxisSize: MainAxisSize.min,
children: [
Padding(
padding: const EdgeInsets.only(bottom: 8.0),
child: Align(alignment: Alignment.centerLeft, child: Text("A csapat tagjai:")),
),
for (Player player in team.players) Text("${player.displayName}(${player.inGameDisplayName})")
],
),
),
actions: [
TextButton(
onPressed: () => Navigator.pop(context),
child: Text(
"Bezárás",
style: TextStyle(color: Colors.white),
)),
Spacer(),
TextButton(
onPressed: () {
// Retrieving the match object from the Cubit.
final Match matchWithoutWinner =
BlocProvider.of<TournamentCubit>(context).getMatchOfTournamentById(tournament, matchId);
// Creating a new match instance containing the winner team.
if (matchWithoutWinner is DoubleEliminationLoserBranchMatch) {
final DoubleEliminationLoserBranchMatch matchWithWinner = DoubleEliminationLoserBranchMatch(
matchWithoutWinner.id,
matchWithoutWinner.team1,
matchWithoutWinner.team2,
team,
matchWithoutWinner.parent1id,
matchWithoutWinner.parent2id);
BlocProvider.of<TournamentCubit>(context).setWinnerOfMatch(tournament, matchWithWinner);
}
else {
final Match matchWithWinner = Match(matchWithoutWinner.id, matchWithoutWinner.team1,
matchWithoutWinner.team2, team, matchWithoutWinner.parent1id, matchWithoutWinner.parent2id);
BlocProvider.of<TournamentCubit>(context).setWinnerOfMatch(tournament, matchWithWinner);
}
Navigator.pop(context);
},
child: Text(
"Beállítás győztesnek",
style: TextStyle(color: Colors.white),
))
],
),
);
}
}
I've found out that the grey box is the release version of the red screen of death. After that, I checked, none of the injected variables are null. There is only one problem in debug:
What could be the problem? Could this cause the issue and how can I fix it?

Answer 1

The cause of the issue was the Spacer() between the two buttons in the actions list, removing it fixed the problem, without changing the UI.