Technically what is happening behind the scenes is that for most languages the compiler/interpreter will promote the integer to a double to avoid foot guns.

Nevertheless integer comparisons with any kind of floating point is not a wise choice.

The idiomatic way to compare a double would be to take into account whatever is the double precision epsilon for that language. Or just use the greater/less than like they have in the subsequent if statements in the original code snippet.

You could have one check such as

  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.