Just curious, but couldn't this be accomplished with

  $#{$array_to_count{$index}}+1
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as well, instead of using the while loop?

That way the code would be

  sub getSecondArraySize {
  
      # receives the argument
      my ($index, %array_to_count) = @_;
      
      # return the count
      return $#{$array_to_count{$index}}+1;
  }
[download]

Thoughts,
-v