Flutter TypeError - Solution

 TypeError: This error occurs when you try to use a variable or object of the wrong type. This can happen when you try to use a String where an int is expected, or when you try to call a method that is not supported by the variable or object. To resolve this error, check that you are using the correct type of variable or object, and that it supports the methods you are calling.

Null check operator used on a null value: This error occurs when you try to use the null check operator (!) on a variable that is null.

Example:

void main() {

  String? message;

  print(message!.toUpperCase());

}

Solution: Make sure that the variable is initialized before you use it, or use a null-aware operator (?.) instead of the null check operator.