game-editor.com

Like the title says, I think that line numbers in the script editor would be very useful.
When the popup with an error references a line, it would be very useful to know where the error is without counting lines!

This has been brought up before, and is something I'll add in the future. For now though you don't have to count lines. In the top right of the script editor it shows what line the cursor is currently on (in the format Ln #).