Solutions

Exercise 1

Refactor the method to use a Result type with a custom error that encapsulates failure details:

public enum TowerUpgradeError
{
     InsufficientResources,
     MaxLevelReached,
     TowerDestroyed
}
public Result<bool, TowerUpgradeError> UpgradeTower(Tower tower)
{
     // Tower upgrading logic...
     if (/* insufficient resources */)
     {
                  return Result.Fail<bool, TowerUpgradeError>(TowerUpgradeError.InsufficientResources);
     }
     else if (/* max level reached */)
     {
                  return Result.Fail<bool, TowerUpgradeError...