if(percentage < 0 or percentage > 1)
{
// Throw error here
}
Also the checks in the if statements in the linked code are redundant since they simply disregard the previous check, they could simply check if percentage < x instead of checking it's within a range sincs the previous check already proved percentage to be > x - 1/10.
To be fair though, this is the kind of code where "if it's stupid and it works, it's not stupid" applies perfectly. While I would make these changes if I had to approve a PR I wouldn't change this in a live codebase just for refactoring purposes, specially because there are better ways to show progress to a user than using Unicode characters, which I think is the real smell here.
