There's not really a blank line added to your document. If you look at the script file in a hex editor, you'll see that it simply ends with an OA
character - which is a newline.
So, really, every line in the file (including the last line) ends with a newline
character. I assume the editor just chooses to render that case visually with a new line, but it doesn't actually exist in the file until you add content to it.
If you look at your file in (for example) VS Code
, it'll render the same way (with a visual blank at the end).