When there’s no prettify-button like “{}” at the bottom of the one-line-code, you will find the module name above the one-line-code. In your example it was “e8815…”

Right click on this name and the last entry of the new menu will help you. I don’t know the correct english expression, in German firefox it’s called “Quelltext einheitlich formatieren”. In the English version it may be called “pretty-printing” or something like this.

That should fix the problems with the missing prettify-button.