行上得到以下构建错误,但我不确定如何解决它:
The method '+' can't be unconditionally invoked because the receiver can be 'nullor adding a null check to the target ('!').dart(unchecked_use_of_nullable_value)
The method 'split' can't be unconditionally invoked because the receiver can be 'null'.or adding a null check to the target ('!'). Open documentation } return LoginPage();