Mrs. Figg said she was going to "kill Mundungus Fletcher" after he....?

From the text:

“He left!” said Mrs. Figg, wringing her hands. “Left to see someone about a batch of cauldrons that fell off the back of a broom! I told him I’d flay him alive if he went, and now look! Dementors! It’s just lucky I put Mr. Tibbies on the case! But we haven’t got time to stand around! Hurry, now, we’ve got to get you back! Oh, the trouble this is going to cause! I will kill him!”