The line length and what Atom thinks about the line length seem to be out of whack.
In the following image, there is no space in that string, and the cursor is at the end of the line!
With the cursor at the end of the line in the above image, I hit
x, and here is the result:
I’ve tried various fonts (Menlo, Monaco, Inconsolata, Fantasque Mono, Fira Mono, Consolas), all had the same issue, though some (e.g. Consolas) were quite small and then I increased the font size and then it happened again.
atom --safe, too. It happened, too.
I’ve tried various themes, including Atom Light. It happened, too.