[v0.77]"Trade" button in Trade window causes Runtime Error crash

Describe the problem. Be as specific as possible!:If you enter Trade Window with someone and click on the "Trade" button you end up getting crashed out of MapleStory.

Edit : Just got the same error clicking on "Cancel"

Edit2: Tested this myself , it turns out the one who "trades you/requests the trade" doesn't crash if they click Trade or Cancel. However the person who accepts the trade(clicks on the circle of the trade pop-up) ends up being crashed out if they click Trade or Cancel.

A trades B ~> B accepts ~> Trade window opens up, if A clicks Trade or Cancel, A won't crash. If B clicks Trade or Cancel, B will crash.

 Images of problem