Unfortunately these things don’t always go to plan and what you might see on the screen to be fact is unfortunately a work around because a special effect shot was not plausible enough.
But they made it work that is what really counts.
I think the plan was he was meant to put out the flames with his foot but that was altered when the effect did not work.
It doesn’t matter what was planned, what matters is what was in the film. I’m not sure if you realize this, but there’s this thing in movies called “editing” where all sorts of planned things get changed.
The burning robe thing may as well be a novelization bit or something from the EU for all it matters.